Matches in ScholarlyData for { ?s <https://w3id.org/scholarlydata/ontology/conference-ontology.owl#abstract> ?o. }
- 5 abstract "Emails are important tools for communication and cooperation, they contain large amount of information and connections to knowledge and data sources. Because of this, it is very important to improve the efficiency of their processing. This paper describes an email search system which integrates full-text search with social search while processing also the attached and linked resources.".
- 562 abstract "Ontology revision is the process of managing an ontology when a new axiom or fact would render it inconsistent. So far, the AGM approach to belief revision has been adapted to work with ontologies. However, when multiple sources are contributing uncertain knowledge about a static domain, an approach that doesn't give priority to incoming information and allows to recover previously discarded axioms is more suited. We describe an ontology revision framework that links symbolic and numerical techniques to allow the consistent evolution of an ontology from the contributions of multiple potentially unreliable sources.".
- 564 abstract "The use of tags to describe Web resources in a collaborative manner has experienced rising popularity among Web users in recent years. The product of such activity is given the name folksonomy, which can be considered as a scheme of organizing information in the users' own way. In this paper, we present a possible way to analyze the tripartite graphs - graphs involving users, tags and resources - of folksonomies and discuss how these elements acquire their meanings through their associations with other elements, a process we call mutual contextualization. In particular, we demonstrate how different meanings of ambiguous tags can be discovered through such analysis of the tripartite graph by studying the tag sf. We also discuss how the result can be used as a basis to better understand the nature of folksonomies.".
- 565 abstract "Ontology maturing as a conceptual process model is based on the assumption that ontology engineering is a continuous collaborative and informal learning process and always embedded in tasks that make use of the ontology to be developed. For supporting ontology maturing, we need lightweight and easy-to-use tools integrating usage and construction processes of ontologies. Within two applications - ImageNotion for semantic annotation of images and SOBOLEO for semantically enriched social bookmarking - we have shown that such ontology maturing support is feasible with the help of Web 2.0 technologies. In this paper, we want to present the conclusions from two evaluation sessions with end users and summarize requirements for further development.".
- 566 abstract "Nowadays it is widely accepted that ontologies, the key technology for the realization of the Semantic Web, are artefacts that are collaboratively and iteratively developed/evolved, shared, evaluated and discussed within communities of knowledge workers. To enhance the potential of ontologies to be collaboratively engineered and be consistently evolved within and between different communities, they must be escorted with rich meta-information describing the conceptualisations they realize, implementation decisions, the rationale for their evolution, as well as the evolution itself. To support the collaborative engineering of ontologies within and across different communities, this paper proposes a framework of (meta-)ontologies for capturing the meta-information that is necessary for interlinking, sharing, and combining knowledge among the parties involved in such a process. The framework is being embedded in the HCOME ontology engineering methodology, and can be applied to the design and implementation of ontology engineering tools towards advancing their interoperability.".
- 567 abstract "In collaborative indexing systems users generate a big amount of metadata by labelling web-based content. These labels are known as tags and form a shared vocabulary. In order to understand the characteristics of that vocabulary, we study structural patterns of these tags by implying the theory of self-organizing systems. Therefore, we utilize the graph theoretic notion to model the network of tags and their valued connections, which represent frequency rates of co-occurring tags. Empirical data is provided by the free-for-all collaborative indexing systems Delicious, Connotea and CiteULike. First, we measure the frequency distribution of co-occurring tags. Secondly, we correlate these tags towards their rank over time. Results indicate a strong relationship among a few tags as well as a notable persistence of these tags over time. Therefore, we make the educated guess that the observed collaborative indexing systems are self-organizing systems towards a shared vocabulary building. Implications on the results are the presence of semantic domains based on high frequency rates of co-occurring tags, which reflect topics of interest among the user community. When observing those semantic domains over time, that information can be used to provide a historical or trend-setting development of the community's interests, thus enhancing collaborative indexing systems in general as well as providing a new tool to develop community-based products and services at the same time.".
- 568 abstract "Ontologies which represent domain knowledge in information systems are efficient to enhance information retrieval. However, domain knowledge is evolving over time and thus it should be also expressible at ontology level. Unfortunately, we consider that ontology evolution is barely study and its basic principles have not been yet precisely defined according to our notion of evolution. In this paper, we have followed a bottom-up approach consisting in a rigorous analysis of the evolution of a particular domain over a significant period of time (namely the WWW series of conference over a decade) to highlight concrete domain knowledge evolutions. We then have generalized and we present a precise set of evolution features that should be offered by ontology metamodels. We also evaluate the modelling capabilities of OWL to represent these features and finally, we show the contribution of ontology evolution support to improve Web information retrieval.".
- 569 abstract "To construct large scale ontologies, two major approaches are discussed by many researchers. One is a cooperative construction of ontologies, and the other is a modularization of ontologies. To combine these two approaches, this paper discusses a framework for supporting cooperative ontology construction based on dependency management among modularized ontologies. In such a situation, one of the key issues is the maintenance of consistency among inter-dependent ontologies because each ontology is revised asynchronously by different developers. In order to realize consistent development of ontologies, the framework provides two functions: to manage the dependencies between ontology modules and to keep and restore consistencies between them when they are influenced by changes of other modules. Furthermore, we outline an implementation of our framework in our environment for building/using ontology: Hozo.".
- 570 abstract "As claimed in the Semantic Web project, a huge amount of physically distributed interacting software agents could find the semantic of available resources and answer more relevantly to users' requests if the content of these resources would be represented with formal semantic concepts defined in ontologies. Because Web information sources are highly dynamic and conceptually heterogeneous, one of the most challenging problems in the Semantic Web research is the proper and frequent ontology updating in keeping with knowledge changes. To tackle this problem, we have developed a self-organizing multi-agent system -Dynamo- able to create an ontology draft from automatic text processing. Because it is well-known that only a part of a domain description is explicitly described in texts, Dynamo enables an ontology co-construction with a domain expert in a fully interactive way. In this paper, we present the principles of this approach and related experiments. ".
- 571 abstract "While the Semantic Web requires a large amount of structured knowledge (triples) to allow machine reasoning, the acquisition of this knowledge still represents an open issue. Indeed, expressing expert knowledge in a given formalism is a tedious process. Less structured annotations such as tagging have, however, proved immensely popular, whilst existing unstructured or semi-structured collaborative knowledge bases such as Wikipedia have proven to be useful and scalable. Both processes are often regulated through social mechanisms such as wiki-like operations, recommendations, ratings, and collaborative games. To promote collaborative tagging as a means to acquire unstructured as well as structured knowledge we introduce the notion of Extreme Tagging, which describes systems which allow the tagging of resources, as well as of tags themselves and their relations. We provide a formal description of extreme tagging followed by examples and highlight the necessity of regulatory processes which can be applied to it. We also present a prototype implementation.".
- 10 abstract "The mathematical nature of description logics has meant that domain experts find it hard to understand. This forms a significant impediment to the creation and adoption of ontologies. This paper describes Rabbit, a Controlled Natural Language that can be translated into OWL with the aim of achieving both comprehension by domain experts and computational preciseness. We see Rabbit as complementary to OWL, extending its reach to those who need to author and understand domain ontologies but for whom OWL is difficult to comprehend even when expressed in more user-friendly forms such as the Manchester Syntax. The paper outlines the main grammatical aspects of Rabbit, which can be broadly classified into declarations, concept descriptions and definitions, and elements to support interoperability between ontologies. The paper also describes the human subject testing that has been performed to date and indicates the changes currently being made to the language following this testing. Further modifications have been based on practical experience result from the application of Rabbit for the development of operational ontologies in the domain of topography.".
- 105 abstract "Content annotations in semantic cultural heritage portals commonly make spatiotemporal references to historical regions and places using names whose meanings are different in different times. For example, historical administrational regions such as countries, municipalities, and cities have been renamed, merged together, split into parts, and annexed or moved to and from other regions. Even if the names of the regions remain the same (e.g., Germany), the underlying regions and their relationships to other regions may change (e.g., the regional coverage of Germany at different times). As a result, representing and finding the right ontological meanings for historical geographical names on the semantic web creates severe problems both when annotating contents and during information retrieval. This paper presents a model for representing the meaning of changing geospatial resources. Our aim is to enable precise annotation with temporal geospatial resources and to enable semantic search and browsing using related names from other historical time periods. A simple model and metadata schema is presented for representing and maintaining geospatial changes from which an explicit time series of temporal part-of ontologies can be created automatically. The model has been applied successfully to representing the complete change history of municipalities in Finland during 1865–2007, and the resulting ontology time series is used in the semantic cultural heritage portal CULTURESAMPO to support faceted semantic search of contents and to visualizing historical regions on overlaying maps originating from different historical eras.".
- 107 abstract "For the effective alignment of ontologies, the computation of equivalence relations between elements of ontologies is not enough: Subsumption relations play a crucial role as well. In this paper we propose the "Classification-Based Learning of Subsumption Relations for the Alignment of Ontologies" (CSR) method. Given a pair of concepts from two ontologies, the objective of CSR is to identify patterns of concepts' features that provide evidence for the subsumption relation among them. This is achieved by means of a classification task, using state of the art supervised machine learning methods. For the learning of the classifiers, CSR generates training datasets from the source ontologies', considering each ontology in isolation: This allows the method to tune itself to the idiosyncrasies of each of the source ontologies. The paper describes thoroughly the method, provides experimental results over an extended version of benchmarking series and discusses the potential of the method.".
- 108 abstract "This paper describes hybrid search, a semantic methodology supporting both document and knowledge retrieval via the flexible combination of ontology-based search and keyword-matching. Hybrid search aims to smoothly cope with lack of semantic coverage of document content, which is one of the main limitations of current semantic search methods. In this paper we define hybrid search formally, discuss its compatibility with the current semantic trends and present a reference implementation: K-Search. We then show how the methodology outperforms both keyword-based search and pure semantic search in terms of precision and recall in a set of experiments performed on a very large collection of documents. Experiments carried out with professional users show that users understand the paradigm and consider it very powerful and reliable. K-Search has been ported to 2 applications released at Rolls-Royce plc for searching technical documentation about jet engines.".
- 11 abstract "Recommender systems face up to current information overload by selecting automatically items that match the personal preferences of each user. The so-called content-based recommenders suggest items similar to those the user liked in the past, by resorting to syntactic matching mechanisms. The rigid nature of such mechanisms leads to recommend only items that bear a strong resemblance to those the user already knows. In this paper, we propose a novel content-based strategy that diversifies the offered recommendations by employing reasoning mechanisms borrowed from the Semantic Web. These mechanisms discover extra knowledge about the user's preferences, thus favoring more accurate and flexible personalization processes. Our approach is generic enough to be used in a wide variety of personalization applications and services, in diverse domains and recommender systems. The proposed reasoning-based strategy has been empirically evaluated with a set of real users. The obtained results evidence computational feasibility and significant increases of recommendation accuracy in relation to existing approaches where our reasoning capabilities are disregarded.".
- 115 abstract "In Web Service Composition (WSC) problems, the composition process generates a solution, i.e., a composition (or a plan) of atomic services, whose execution achieves some objectives on the Web. Existing research on Web service composition generally assumed that these objectives are absolute; i.e., the service-composition algorithms must achieve all of them in order to generate successful outcomes; otherwise, the composition process fails altogether. The most straightforward example is the use of OWL-S process models that specifically tell a composition algorithm how to achieve a functionality on the Web. However, in many WSC problems, it is also desirable to achieve users' preferences that are not absolute objectives, but a solution composition generated by a WSC algorithm must satisfy those preferences as much as possible. In this paper, we first describe a way to augment OWL-S process models by qualitative user preferences. We achieve this by mapping a given set of process models and preferences into a planning language for representing Hierarchical Task Networks (HTNs). We then present SCUP, our new WSC algorithm that performs a best-first search over the possible HTN-style task decompositions by heuristically scoring those decompositions based on ontological reasoning over the input preferences. Finally, we discuss our theoretical and experimental results on the SCUP algorithm.".
- 119 abstract "With currently available tools and languages, translating between an existing XML format and RDF is a tedious and error-prone task. The importance of this problem is acknowledged by the W3C GRDDL working group who faces the issue of extracting RDF data out of existing HTML or XML files, as well as by the Web service community around SAWSDL, who need to perform lowering and lifting between RDF data from a semantic client and XML messages for a Web service. However, at the moment, both these groups rely solely on XSLT transformations between RDF/XML and the respective other XML format at hand. In this paper, we propose a more natural approach for such transformations based on merging XQuery and SPARQL into the novel language XSPARQL. We demonstrate that XSPARQL provides concise and intuitive solutions for mapping between XML and RDF in either direction, addressing both the use cases of GRDDL and SAWSDL. We also provide and describe an initial implementation of an XSPARQL engine, available for user evaluation.".
- 12 abstract "In the e-Science context, workflow technologies provide a problem-solving environment for researchers by facilitating the creation and execution of experiments from a pool of available services. In this paper we will show how Semantic Web technologies can be used to overcome a limitation of current workflow languages by capturing experimental constraints and goals, which we term scientist's intent. We propose an ontology driven framework for capturing such intent based on workflow metadata combined with SWRL rules. Through the use of an example we will present the key benefits of the proposed framework in terms of enriching workflow output, assisting workflow execution and provenance support. We conclude with a discussion of the issues arising from application of this approach to the domain of social simulation.".
- 120 abstract "We introduce domain-restricted RDF (dRDF) which allows to associate an RDF graph with a fixed, finite domain that interpretations for it may range over. We show that dRDF is a real extension of RDF and discuss impacts on the complexity of entailment in dRDF. The entailment problem represents the key reasoning task for RDF and is well known to be NP-complete. Remarkably, we show that the restriction of domains in dRDF raises the complexity of entailment from NP- to $\Pi^P_2$-completeness. In order to lower complexity of entailment for both domain-restricted and unrestricted graphs, we take a closer look at the graph structure. For cases where the structure of RDF graphs is restricted via the concept of bounded treewidth, we manage to prove tractability of entailment. We also present a polynomial entailment checking algorithm for such graphs.".
- 130 abstract "Participants at both end of the communication channel must share common pictogram interpretation to communicate. However, because pictogram interpretation can be ambiguous, pictogram communication can sometimes be difficult. To assist human task of selecting pictograms more likely to be interpreted as intended, we propose a semantic relevance measure which calculates how relevant a pictogram is to a given interpretation. The proposed measure uses pictogram interpretations and frequencies gathered from a web survey to define probability and similarity measurement of interpretation words. Moreover, the proposed measure is applied to categorized pictogram interpretations to enhance retrieval performance. Five pictogram categories are created using the five first-level concepts defined the Concept Dictionary of EDR Electronic Dictionary. Retrieval performace among non-categorized interpretations, categorized and non-weighted interpretations, and categorized and weighted interpretations using semantic relevance measure were compared, and the weighted and categorized semantic relevance approach exhibited highest precision and recall.".
- 133 abstract "This research explores our novel method for Semantic Web service matchmaking based on iSPARQL queries, which enable the user to query the Semantic Web with techniques from traditional information retrieval. The strategies for matchmaking which we develop and evaluate in the paper make use of a plethora of similarity measures and combination functions from SimPack -- our library of similarity measures for the use in ontologies. We show how our combination of structured and imprecise querying can be used to perform hybrid Semantic Web service matchmaking in simple and amazingly fast fashion. We analyze our approach thoroughly on a large OWL-S service test collection, and show how our initial strategies can be improved by applying machine learning algorithms such as regression, decision trees, or support vector machines to result in the most effective strategies for matchmaking.".
- 14 abstract "The description logic EL+ has recently proved practically useful in the life science domain with presence of several large-scale biomedical ontologies such as SNOMED CT. To deal with ontologies of this scale, standard reasoning of classification is essential but not sufficient. The ability to extract relevant fragments from a large ontology and to incrementally classify it has become more crucial to support ontology design, maintenance and re-use. In this paper, we propose a pragmatic approach to module extraction and incremental classification for EL+ ontologies and report on empirical evaluations of our algorithms which have been implemented as an extension of the CEL reasoner.".
- 141 abstract "Ontology-Driven Software Development (ODSD) advocates using ontologies for capturing knowledge about a software system at development time. So far, ODSD approaches have mainly focused on the unambiguous representation of domain models during the system analysis phase. However, the design and implementation phases can equally benefit from the logical foundations and reasoning facilities provided by the Ontology technological space. This applies in particular to model-driven approaches that employ models as first class entities throughout the entire software development process. We are currently developing a toolsuite called HybridMDSD that employs Semantic Web technologies to integrate different domain-specific modeling languages based on their ontological foundations. To this end, we have defined a new upper ontology for software models that complements existing work in conceptual and business modeling. This paper describes the structure and axiomatization of our ontology and its underlying conceptualization. Further, we report on the experiences gained with validating the integrity and consistency of software models using a Semantic Web reasoning architecture. We illustrate practical solutions to the problems arising from the open-world assumption in OWL and lack of nonmonotonic queries in SWRL.".
- 146 abstract "Most of the challenges faced when building the Semantic Web require a substantial amount of human labor and intelligence. Despite significant advancement in ontology learning and human language technology, building ontologies, annotating data, and establishing alignments between multiple ontologies remain tasks that highly depend on human intelligence, both as a source of domain expertise and for specifying the results. This means that individuals need to contribute time, and sometimes other resources. Now, we can observe a sharp contrast in user interest in two branches of Web activity: While the “Web 2.0�? movement lives from an unprecedented amount of contributions from Web users, we witness a substantial lack of user involvement in the aforementioned tasks . We assume that one cause of the latter is a lack of proper incentive structures, i.e., settings in which the perceived benefits outweigh the efforts for people to contribute. As a novel solution, we (1) propose to masquerade the core tasks of weaving the Semantic Web behind on-line, multi-player game scenarios, in order to create proper incentives for humans to get involved. Doing so, we adopt the findings from the already famous “games with a purpose�? by von Ahn, who has shown that presenting a useful task, which requires human intelligence, in the form of an on-line game can motivate a large amount of people to work heavily on this task, and this for free. Then, we (2) describe our OntoGame prototypes, (3) provide preliminary evidence that users are willing to invest a lot of time into those games, (4) show that the users’ input creates reliable results, and (5) discuss how, by doing so, they unknowingly weave the Semantic Web.".
- 152 abstract "The establishment of the architecture of any information system is one of the crucial activities during the design and implementation thereof. There is general consensus in literature that an architecture (at least) depicts the structure of a system within a specific context. This depicted structure should portray the components that a system comprises of, as well as the relationships between the identified components. One of the main purposes of a system architecture is the provision of an agreed-upon functional description of system structure, components and component interactions. It is thus plausible to state that an architecture for the Semantic Web is crucial to its eventual realisation and that it is therefore necessary to attach undisputable meaning to the specification of the architecture for the languages of the Semantic Web. The most well-known versions of the layered architecture that exist within literature have been proposed by Berners-Lee, and the literature offers no description or specification of meaning for any of these. Furthermore, it is possible to indicate inconsistencies and discrepancies in the different versions of the architecture, leading to confusion, as well as conflicting proposals and adoptions by the Semantic Web community. In addition, none of the current formal initiatives by the W3C address the Semantic Web architecture specifically, which could be regarded as an omission. A layered architecture for the Semantic Web that adheres to Software Engineering principles and the fundamental aspects of layered architectures will assist in the development of Semantic Web specifications and applications. Furthermore, several of the current research and implementation issues associated with the implementation of the Semantic Web could potentially be resolved. A more recent version of a Semantic Web layered architecture, namely the CFL architecture, was proposed by Gerber, van der Merwe and Barnard [1]. They claim that their abstracted CFL architecture of the Semantic Web adheres to Software Engineering principles and addresses several of the concerns evident from previous versions of the architecture. In this paper we evaluate this recent architecture, both by scrutinising the shortcomings of previous architectures and evaluating the approach used for the development of the latest architecture. A similar approach was used in the construction of one of the most significant layered architectures in popular use today, notably the ISO/OSI reference model for network protocols. Furthermore, the CFL architecture is applied to usage scenarios to evaluate the usefulness thereof. We reach the conclusion that the approach indeed has merit in resolving current issues with regards to the architecture of the languages of the Semantic Web. However, the proposed version needs to be refined through consensus by all role players, including the W3C. Reference: [1] Gerber A.J., Van der Merwe A.J. and Barnard A., Towards a Semantic Web Layered Architecture. In Proceedings of the International Conference on Software Engineering (IASTED SE2007), Innsbruck, Austria, February 2007, pp.353-362.".
- 159 abstract "Knowledge work in many fields requires examining several aspects of a collection of documents to attain meaningful understanding that is not explicitly available. Despite recent advances in document corpus visualization research, there is still a lack of principled approaches which enable the users to personalize the exploratory analysis process. In this paper, we present IVEA (Information Visualization for Exploratory Document Collection Analysis), an innovative visualization tool which employs the PIMO (Personal Information Model) ontology to provide the knowledge workers with an interactive interface allowing them to browse for information in a personalized manner. Not only does the tool allow the users to integrate their personal knowledge into the exploration and analysis of a document collection, it also enables them to incrementally enrich their PIMO ontologies with new entities matching their evolving interests in the process, benefiting the users not only in their future experience with IVEA but also with other PIMO-based applications. The usability of the tool was preliminarily evaluated and the results were sufficiently encouraging to make it worthwhile to conduct a larger-scale usability study.".
- 168 abstract "Integrated access to multiple distributed and autonomous RDF data sources is a key challenge for many semantic web applications. As a reaction to this challenge, SPARQL, the current W3C Proposed Recommendation for an RDF query language, supports querying of multiple RDF graphs. However, the current standard does not provide transparent query federation, which makes query formulation hard and lengthy. Furthermore, current implementations of SPARQL load all RDF graphs mentioned in a query to the local machine. This usually incurs a large overhead in network traffic, and sometimes is simply impossible for technical or legal reasons. To overcome these problems we present DARQ, an engine for federated SPARQL queries. DARQ provides transparent query access to multiple SPARQL services, i.e., it gives the user the impression to query one single RDF graph despite the real data being distributed on the web. A service description language enables the query engine to decompose a query into sub-queries, each of which can be answered by an individual service. DARQ also uses query rewriting and cost-based query optimization to speed-up query execution. Experiments show that these optimizations significantly improve query performance even when only a very limited amount of statistical information is available. DARQ is available under GPL License at http://darq.sf.net/.".
- 186 abstract "Context-awareness is a highly desired feature across several application domains. Semantic Web Services (SWS) technologies address context-adaptation by enabling the automatic discovery of distributed Web services for a given task based on comprehensive semantic representations. Whereas SWS technology supports the allocation of resources based on semantics, it does not entail the discovery of appropriate SWS representations for a given situation. Describing the complex notion of a situation in all its facets through symbolic SWS representation facilities is a costly task which may never lead to semantic completeness and introduces ambiguity issues. Moreover, even though not any real-world situation completely equals another, it has to be matched to a finite set of parameter descriptions within SWS representations to enable context-adaptability. To overcome these issues, we propose Conceptual Situation Spaces (CSS) to facilitate the description of situation characteristics as members in geometrical vector spaces following the idea of Conceptual Spaces. CSS enable fuzzy similarity-based matchmaking between real-world situation characteristics and predefined situation descriptions. Following our vision, the latter are part of semantic Situation-Driven Process (SDP) descriptions, which define a composition of SWS Goals suitable to support the course of an evolving situation. Particularly, we refer to the WSMO approach for SWS. Consequently, our approach extends the expressiveness of WSMO by enabling the automatic discovery, composition and execution of achievable goals for a given situation. To prove the feasibility, we apply our approach to the domain of eLearning and provide a proof-of-concept prototype.".
- 188 abstract "Thesaurus alignment plays an important role in realising efficient access to heterogeneous Cultural Heritage data. Current ontology alignment techniques, however, provide only limited value for such access as they consider little if any requirements from realistic use cases or application scenarios. In this paper, we focus on two real-world scenarios in a library context: thesaurus merging and book re-indexing. We identify their particular requirements and describe our approach of deploying and evaluating thesaurus alignment techniques in this context. We have applied our approach for the Ontology Alignment Evaluation Initiative, and report on the performance evaluation of participants’ tools wrt. the application scenario at hand. It shows that evaluations of tools requires significant effort, but when done carefully, brings many benefits.".
- 199 abstract "Accessing structured data such as that encoded in ontologies and knowledge bases can be done using either syntactically complex formal query languages like SPARQL or complicated form interfaces that require expensive customisation to each particular application domain. This paper presents the QuestIO system { a natural language interface for accessing structured information, that is domain independent and easy to use without training. It aims to bring the simplicity of Google's search interface to conceptual retrieval by automatically converting short conceptual queries into formal ones, which can then be executed against any semantic repository. QuestIO was developed specifically to be robust with regard to language ambiguities, incomplete or syntactically ill-formed queries, by harnessing the structure of ontologies, fuzzy string matching, and ontology-motivated similarity metrics.".
- 207 abstract "The Semantic Desktop is a means to support users in Personal Information Management (PIM). It provides an excellent test bed for Semantic Web technology: resources (e. g., persons, projects, messages, documents) are distributed amongst multiple systems, ontologies are used to link and annotate them. Finding information is a core element in PIM. For the end user, the search interface has to be intuitive to use, natural language queries provide a simple mean to express requests. State of the art semantic search engines focus on metadata search or on semantic document retrieval. We combine both approaches to search the Semantic Desktop exploiting all available information, where we build on semantic teleporting and spreading activation. This combination is able to answer queries with instances, subgraphs of the knowledge base, and with relevant documents. We evaluated our approach on ESWC 2007 data in comparison with Google site search.".
- 209 abstract "Dissemination, an important phase of scientific research, can be seen as a communication process between scientists. They expose and support their findings, while discussing claims stated in related scientific publications. However, due to the increasing number of publications, finding a starting point for such a discussion represents a real challenge. At same time, browsing can also be difficult since the communication spans across multiple publications on the open web. In this paper we propose a semantic claim federation infrastructure, named KonneX-SALT, as a solution for both issues mentioned above: (i) finding claims in scientific publications, and (ii) building the argumentation discourse network (ADN) for each claim and providing support for browsing it (in our case, by making use of transclusion). In addition, we join the web of "linked open data", by linking the metadata managed by KonneX-SALT with some of the known repositories of scientific publications.".
- 222 abstract "Several approaches to semantic Web services, including OWL-S, SWSF, and WSMO, have been proposed in the literature with the aim to enable automation of various tasks related to Web services, such as discovery, contracting, enactment, monitoring, and mediation. The ability to specify processes and to reason about them is central to these initiatives. In this paper we analyze the WSMO choreography model, which is based on Abstract State Machines (ASMs), and propose a methodology for generating WSMO choreography from visual specifications. We point out the limitations of the current WSMO model and propose a faithful extension that is based on Concurrent Transaction Logic (CTR). The advantage of a CTR-based model is that it uniformly captures a number of aspects that previously required separate mechanisms or were not captured at all. These include process specification, contracting for services, service enactment, and reasoning.".
- 244 abstract "In this contribution a system is presented, which provides access to distributed data sources using Semantic Web technology. While it was primarily designed for data sharing and scientific collaboration, it is regarded as a base technology useful for many other Semantic Web applications. The proposed system allows to retrieve data using SPARQL queries, data sources can register and abandon freely, and all RDF Schema or OWL vocabularies can be used to describe their data, as long as they are accessible on the Web. Data heterogeneity is addressed by RDF-wrappers like D2R-Server placed on top of local information systems. A query does not directly refer to actual endpoints, instead it contains graph patterns adhering to a virtual data set. A mediator finally pulls and joins RDF data from different endpoints providing a transparent on-the-fly view to the end-user. The SPARQL protocol has been defined to enable systematic data access to remote endpoints. However, remote SPARQL queries require the explicit notion of endpoint URIs. The presented system allows users to execute queries without the need to specify target endpoints. Additionally, it is possible to execute join and union operations across different remote endpoints. The optimization of such distributed operations is a key factor concerning the performance of the overall system. Therefore, proven concepts from database research can be applied.".
- 245 abstract "Today, as a result of many independent initiatives, research projects and commercial initiatives, relatively large and important content repositories are available which actually are (or can be easily tranformed into) local ``semantic webs'', namely graphs of resources connected through properties which are defined in some schema or vocabulary. The data published as part of the LinkedData initiative are examples of content already insemantic web format (RDF/OWL); however, any social network, digital library metadata collection, commercial catalog and in principle any relational database could be easily (and mostly syntactically) transformed into a local semantic web. So what is missing enabling factor which can support the automatic and smooth integration of these local ``semantic webs'' into something like the envisaged global Semantic Web? In this paper, we argue that the missing factor is a service which, in analogy with what the DNS did for the Web, can make the addressing mechanism of the Semantic Web global. The addressing mechanism of the WWW was made global by building it on top of the pre-existing DNS service; the addressing mechanism of the Semantic Web cannot go global, as no such pre-existing infrastructure is available, and therefore no fast and easy (semantic) integration is readily available. In this paper, we first introduce and describe what we consider to be the cornerstone of such an infrastructure, a service called Entity Naming System (ENS) which is designed to resolve a local URI or even an arbitrary description of a resource (not only, and not mainly, information resources) into a global identifier for that resource. Then we discuss the main issues and challenges associated with the design and implementation of a scalable and sustainable ENS. Third, we report the results of an experiment which we made on integrating the metadata of several Web and Semantic Web conference with or without a ENS. Finally, we present two simple examples of how existing applications can use the ENS for creating semantically integrated knowledge for the Semantic Web.".
- 246 abstract "The original Semantic Web vision was explicit in the need for intelligent autonomous agents that would represent users and help them navigate the Semantic Web. We argue that an essential feature for such agents is the capability to analyse data and learn. In this paper we outline the challenges and issues surrounding the application of clustering algorithms to Semantic Web data. We present several ways to extract instances from a large RDF graph and computing the distance between these. We evaluate our approaches on three different data-sets, one representing a typical relational database to RDF conversion, one based on data from a ontologically rich Semantic Web enabled application, and one consisting of a crawl of FOAF documents; applying both supervised and unsupervised evaluation metrics. Our evaluation did not support choosing a single combination of instance extraction method and similarity metric as superior in all cases, and as expected the behaviour depends greatly on the data being clustered. Instead, we attempt to identify characteristics of data that make particular methods more suitable.".
- 252 abstract "In the context of Semantic Web, deductive reasoning is used for making explicit the implicit knowledge of a knowledge base (KB). Anyway, purely logic-based approaches can fail when data comes from distributed sources, where contradictions usually turn out. Inductive instance-based learning methods can be effectively used in such a case, since they are well known to be efficient and fault tolerant. In this paper we propose an inductive method for improving the concept retrieval and for the performing the ontology population in a (semi-)automatic way. By casting concept retrieval to a classification problem with the goal of assessing the individual memberships w.r.t. the query concepts, we propose an extension of the \emph{k-Nearest Neighbor} algorithm for Description Logic KBs. It is based on the exploitation of an \emph{entropy}-based dissimilarity measure. The procedure retrieves individuals belonging to query concepts, by analogy with other training instances, on the grounds of the classification of the nearest ones w.r.t.\ the dissimilarity measure. We experimentally show that the behavior of the classifier is comparable with the one of a standard reasoner. Moreover we show that new knowledge (not logically derivable) is induced. It can be suggested to the knowledge engineer for validation, during the ontology population task.".
- 260 abstract "In semantic web applications where query initiators and information providers do not necessarily share the same ontology, semantic interoperability typically relies on ontology matching or schema mappings. Information exchange is then not only enabled by the established correspondences (the ``shared'' parts of the ontologies) but, in some sense, limited to them. Then, an important question which has not received attention is how the ``unshared'' parts can also contribute to and improve information exchange. In this paper, we address this question by considering a system where documents and queries are represented by semantic vectors. We propose a specific query expansion step at the query initiator's side and a query interpretation step at the document provider's. Through these steps, unshared concepts contribute to evaluate the relevance of documents wrt. a given query. Our experiments show an important improvement of retrieval relevance when concepts of documents and queries are not shared. Even if the concepts of the initial query are not shared by the document provider, our method still ensures 90% of the precision and recall obtained when the concepts are shared.".
- 265 abstract "Driven by application requirements and using well-understood theoretical results, we describe a novel methodology and a tool for modular ontology design. We support the user in the safe use of imported symbols and in the economic import of the relevant part of the imported ontology. Both features are supported in a well-understood way: safety guarantees that the semantics of imported concepts is not changed, and economic import guarantees that no difference can be observed between importing the whole ontology and importing the relevant part.".
- 273 abstract "We present a method based on clustering techniques to detect concept drift or novelty in a knowledge based expressed in Description Logics. The method exploits an effective and language-independent semi-distance measure defined for the space of individuals, that is based on a finite number of dimensions corresponding to a committee of discriminating features (represented by concept descriptions). A maximally discriminating group of features can be obtained with the randomized optimization methods described in the paper. An experimentation with some ontologies proves the feasibility of our method and its effectiveness in terms of clustering validity indices. Then, with a supervised learning phase, each cluster can be assigned with a refined or newly constructed intensional definition expressed in the adopted language. We propose a method for exploiting the clustering results for concept drift and novelty detection".
- 281 abstract "Current efforts in Semantic Web Services do not sufficiently address the industrial developments of SOA technology in regards to bottom-up modeling of services, that is, building incremental layers on top of existing service descriptions. An important step in this direction has been made in the W3C by the SAWSDL WG proposing a framework for annotating WSDL services with arbitrary semantic descriptions. We build on the SAWSDL layer and define WSMO-Lite service ontology, narrowing down the use of SAWSDL as an annotation mechanism for WSMO-Lite. Ultimately, our goal is to allow incremental steps on top of existing service descriptions, enhancing existing SOA capabilities with intelligent and automated integration.".
- 284 abstract "Typically ontologies are described in a determined natural language. Organizations working in a multilingual environment demand multilingual ontologies. To solve this problem we propose LabelTranslator, a NeOn plug-in that automatically localize ontologies. Ontology localization consists in adapting an ontology to a concrete language and culture community. LabelTranslator takes as input an ontology whose labels are described in a source natural language and obtains the most probable translation of each ontology label in a target natural language. Our main contribution is the automatization of this process which reduces human efforts to localize manually the ontology. First, our system uses a translation service which obtains automatic translations of each ontology label (name of an ontology term) in English, German, or Spanish by consulting different linguistic resources such as lexical databases, bilingual dictionaries, and terminologies. Second, a ranking method is used to sort each ontology label according to similarity with its lexical and structural context. The experiments performed in order to evaluate the quality of translation show that our approach is a good approximation to enrich an ontology with multilingual information.".
- 291 abstract "The semantics of OWL-DL and its subclasses are based on the classical semantics of first-order logic, in which the interpretation domain may be an infinite set. This constitutes a serious expressive limitation for such ontology languages, since, in many real application scenarios for the Semantic Web, the domain of interest is actually finite, although the exact cardinality of the domain is unknown. Hence, in these cases the formal semantics of the OWL-DL ontology does not coincide with its intended semantics. In this paper we start filling this gap, by considering the subclasses of OWL-DL which correspond to the logics of the DL-Lite family, and studying reasoning over finite models in such logics. In particular, we mainly consider two reasoning problems: deciding satisfiability of an ontology, and answering unions of conjunctive queries (UCQs) over an ontology. We first consider the description logic DL-Lite_R and show that, for the two above mentioned problems, finite model reasoning coincides with classical reasoning, i.e., reasoning over arbitrary, unrestricted models. Then, we analyze the description logics DL-Lite_F and DL_Lite_A. Differently from DL-Lite_R, in such logics finite model reasoning does not coincide with classical reasoning. To solve satisfiability and query answering over finite models in these logics, we define techniques which reduce polynomially both the above reasoning problems over finite models to the corresponding problem over arbitrary models. Thus, for all the DL-Lite languages considered, the good computational properties of satisfiability and query answering under the classical semantics also hold under the finite model semantics. Moreover, we have effectively and easily implemented the above techniques, extending the DL-Lite reasoner QuOnto with support for finite model reasoning.".
- 292 abstract "Business Process Management (BPM) aims at supporting the whole life-cycle necessary to deploy and maintain business processes in organisations. An important step of the BPM life-cycle is the analysis of the processes deployed in companies. However, the degree of automation currently achieved cannot support the level of adaptation required by businesses. Initial steps have been performed towards including some sort of automated reasoning within Business Process Analysis (BPA) but this is typically limited to using taxonomies. We present a core ontology aimed at enhancing the state of the art in BPA. The ontology builds upon a Time Ontology and is structured around the process, resource, and object perspectives as typically adopted when analysing business processes. The ontology has been extended and validated by means of an Events Ontology and an Events Analysis Ontology aimed at capturing the audit trails generated by Process-Aware Information Systems and deriving additional knowledge.".
- 293 abstract "Instant Messaging is in addition to Web and Email the most popular service on the Internet. With xOperator we present a strategy and implementation which deeply integrates Instant Messaging networks with the Semantic Web. The xOperator concept is based on the idea of creating an overlay network of collaborative information agents on top of social IM networks. It can be queried using a controlled and easily extensible language based on AIML templates. Such a deep integration of semantic technologies and Instant Messaging bears a number of advantages and benefits for users when compared to the separated use of Semantic Web technologies and IM, the most important ones being context awareness as well as provenance and trust. We showcase how the xOperator approach naturally facilitates contacts and calendar management as well as access to large scale heterogeneous information sources.".
- 3 abstract "A lot of work has been done in the area of data stream processing. Most of the previous approaches regard only relational or XML based streams but do not cover semantic richer RDF based stream elements. In our work, we extend SPARQL, the W3C recommendation for an RDF query language, to process RDF data streams. To describe the semantics of our enhancement, we extended the logical SPARQL algebra for stream processing on the foundation of a temporal relational algebra based on multi sets and provide an algorithm to transform SPARQL queries to the new extended algebra. For each logical algebra operator, we defined executable physical counterparts. To show the feasibility of our approach, we implemented it within our ODYSSEUS framework in the context of wind power plant monitoring.".
- 32 abstract "In machine learning/data mining, people have been exploring how to learn models of relational data for a long time. The rational behind this is that exploiting the rich and complex structure of relational data enables to build better models by taking into account the additional information provided by the links between objects. These links are usually hard to model by traditional propositional learning techniques. We extend this idea to the Semantic Web. In this paper we introduce a novel approach we call SPARQL-ML to perform data mining for Semantic Web data. Our approach is based on traditional SPARQL and statistical relational learning methods, such as Relational Probability Trees and Relational Bayesian Classifiers. We analyze our approach thoroughly conducting three sets of experiments on synthetic as well as real-world datasets. Our analytical results show that our approach can be used for any Semantic Web dataset to perform instance-based learning and classification. A comparison to kernel methods used in Support Vector Machines shows that our approach is superior in terms of classification accuracy. Moreover, we show how our approach can be used for Semantic Web service classification and automatic semantic annotation.".
- 325 abstract "In this paper, we introduce a formal email workflow model based on traditional email, which enables the user to define and execute ad-hoc workflows in an intuitive way. This model paves the way for semantic annotation of implicit, well-defined workflows, thus making them explicit and exposing the missing information in a machine processable way. Grounding this work within the Social Semantic Desktop [1] via appropriate ontologies means that this information can be exploited for the benefit of the user. This will have a direct impact on their personal information management - given email is not just a major channel of data exchange between desktops, but it also serves as a virtual working environment where people collaborate. Thus the presented workflow model will have a concrete manifestation in the creation, organization and exchange of semantic desktop data.".
- 330 abstract "Graphs are increasingly used to model data in many disciplines. Structure search which matches a query graph against a data graph, is a common information retrieval paradigm for graph structured data. A crucial factor in optimizing such searches is the ability to estimate the frequency of substructures within a query graph. In this work, we present and evaluate two techniques for estimating the frequency of subgraphs from a summary of the data graph. In the first technique, we assume that edge occurrences on edge sequences are position independent and summarize only the most informative dependencies. In the second technique, we prune small subgraphs based on a valuation scheme that blends information about their importance and estimation power. In both techniques, we assume conditional independence to estimate the frequencies of larger subgraphs. We validate the effectiveness of our techniques using experiments on real and synthetic datasets".
- 346 abstract "Evaluation of ontology alignments is in practice done in two ways: (1) assessing individual correspondences and (2) comparing the alignment to a reference alignment. However, this type of evaluation does not guarantee that an application which uses the alignment will perform well. In this paper, we contribute to the current ontology alignment evaluation practices by proposing two alternative evaluation methods that take into account some characteristics of a usage scenario without doing a full-fledged end-to-end evaluation. We compare different evaluation approaches in three case studies, focussing on methodological issues. Each case study considers an alignment between a different pair of ontologies, ranging from rich and well-structured to small and poorly structured. This enables us to conclude on the use of different evaluation approaches in different settings.".
- 356 abstract "Increasing amounts of RDF data are available on the Web for consumption by Semantic Web browsers and indexing by Semantic Web search engines. Current Semantic Web publishing practices, however, do not directly support efficient discovery and high-performance retrieval by clients and search engines. We propose an extension to the Sitemaps protocol which provides a simple and effective solution: Data publishers create Semantic Sitemaps to announce and describe their data so that clients can choose the most appropriate access method. We show how this protocol enables an extended notion of authoritative information across different access methods.".
- 36 abstract "This paper presents an automatic method for differentiating between instances and classes in a large scale taxonomy induced from the Wikipedia category network. The method exploits characteristics of the category names and the structure of the network. The approach we present is the first attempt to make this distinction automatically in a large scale resource. In contrast, WordNet and Cyc rely on manual annotations. The result of the process is evaluated against ResearchCyc. On the subnetwork shared by our taxonomy and ResearchCyc we report 84.52% accuracy.".
- 37 abstract "Images play a vital role in scientific studies. An image repository would become a costly and meaningless data graveyard without descriptive metadata. We adapted EPrints, a conventional repository software system, to create a biological research image repository for a local research group, in order to publish images with structured metadata with a minimum of development effort. However, in its native installation, this repository cannot easily be linked with information from third parties, and the user interface has limited flexibility. We address these two limitations by providing Semantic Web access to the contents of this image repository, causing the image metadata to become programmatically accessible through a SPARQL endpoint and enabling the images and their metadata to be presented in more flexible faceted browsers, jSpace and Exhibit. We show the feasibility of publishing image metadata on the Semantic Web using existing tools, and examine the inadequacies of the Semantic Web browsers in providing effective user interfaces. We highlight the importance of a loosely coupled software framework that provides a lightweight solution and enables us to switch between alternative components.".
- 375 abstract "UDDI registries are included as a standard offering within the product suite of any major SOA vendor, serving as the foundation for establishing design-time and run-time SOA governance. Despite the success of the UDDI specification and its rapid uptake by the industry, the capabilities of its offered service discovery facilities are rather limited. The lack of machine-understandable semantics in the technical specifications and classification schemes used for retrieving services, prevent UDDI registries from supporting fully automated and thus truly effective service discovery. This paper presents the implementation of a semantically-enhanced registry that builds on the UDDI specification and augments its service publication and discovery facilities to overcome the aforementioned limitations. The proposed solution combines the use of SAWSDL for creating semantically annotated descriptions of service interfaces and the use of OWL-DL for modelling service capabilities and for performing matchmaking via DL reasoning.".
- 41 abstract "One relevant aspect in the development of the Semantic Web framework is the achievement of a real inter-agents communication capability at the semantic level. The agents should be able to communicate and understand each other using standard communication protocols freely, that is, without needing a laborious a priori preparation, before the communication takes place. For that setting we present in this paper a proposal that promotes to describe standard communication protocols using Semantic Web technology (specifically, OWL-DL and SWRL). Those protocols are constituted by communication acts. In our proposal those communication acts are described as terms that belong to a communication ontology, that we have developed, called CommOnt. The intended semantics associated to the communication acts in the ontology is expressed through social commitments that are formalized as fluents in the Event Calculus. In summary, by taking benefit of OWL-DL reasoners and rule engines our proposal allows to reason about protocols in such a way that the following relations can be discovered: equivalence, specialization, overlapping or disjunction between protocols used by different agents.".
- 42 abstract "This paper concerns versioning services over Semantic Web repositories. At first we introduce an abstract model of versioning services and subsequently we elaborate on storage policies for enabling these services. Specifically, we propose a novel storage policy that exploits the fact that RDF graphs have not a unique serialization (as it happens with texts). For this reason we introduce a storage structure for versioning that is based on partial orders. We discuss the comparative benefits and drawbacks of this approach in terms of storage space and efficiency both analytically and experimentally. For the latter case we report experimental results over large synthetic data sets and we provide efficient algorithms for version creation and retrieval.".
- 54 abstract "This article presents the vision and a framework for creating a national level ontology and ontology service infrastructure in Finland. Core parts of the system and ontologies have been implemented in a national project FinnONTO 2003-2007 funded by 37 companies and public organizations, and are being used it practice for creating semantic portals for eCulture, eHealth, eLearning, and eGovernment. The novelty of the FinnONTO infrastructure is based on two ideas. First, a system national of open source core ontologies is being developed by transforming thesauri in use into lightweight ontologies. The system is based an a large cross-domain top ontology, the General Finnish Ontology YSO, that is then extended by domain specific ontologies aligned with YSO and each other. Collaborative development of such a system of mutually aligned ontologies is supported for obtaining interoperability in their usage in applications. Second, the ONKI Ontology Server framework for publishing ontologies as ready to use services has been implemented. In contrast to earlier ontology servers, ONKI provides legacy and other applications with ready to use functionalities for using ontologies on the HTML level by Ajax and semantic widgets. The idea is to use ONKI for creating mash-up applications in a way analogous to using Google, Yahoo, or Nokia Maps, but in our case external applications are mashed-up with ontology support for, e.g, indexing content or semantic search using semantic autocompletion and disambiguation in a multi-lingual context.".
- 56 abstract "Description logics form the foundation of ontologies used in the Semantic Web. To support reuse and integration of ontologies in Semantic Web applications, it is often necessary to restrict ontologies to a subset of their concepts and roles, or equivalently to forget a complementary subset of concepts and roles from the ontologies. We present the first detailed account of this problem for description logics, in particular for the DL-Lite family of description logics. Specifically, we present a semantic definition of forgetting that generalises the standard definition for classical logic. We introduce algorithms for forgetting concepts roles from both DL-Lite TBoxes and ABoxes. We prove the algorithms are sound and complete with respect to the semantics, and demonstrate how they can be used to speed-up query answering in DL-Lite knowledge bases.".
- 63 abstract "The increasing amount of data on the Semantic Web offers opportunities for semantic search. However, formal query hinders the casual users in expressing their information need as they might be not familiar with the query's syntax or the underlying ontology. Because keyword interfaces are easier to handle for casual users, many approaches aim to translate keywords to formal queries. However, these approaches yet feature only very basic query ranking and do not scale to large repositories. We tackle the scalability problem by proposing a novel clustered-graph structure that corresponds to only a summary of the original ontology. The so reduced data space is then used in the exploration for the computation of top-k queries. Additionally, we adopt several mechanisms for query ranking, which can consider many factors such as the query length and the relevance of ontology elements w.r.t. the query. Our experimental results performed against our implemented system Q2Semantic show that we achieve good performance on many datasets of different sizes.".
- 72 abstract "The need for adaptive and personalized Rich Internet Application puts a new dimension to already existing approaches of Adaptive Hypermedia Systems. Instead of computing the adaptation steps at the server, Rich Internet Applications need a client-side approach that can react immediately on user input. In this paper we present a novel approach that holistically combines page annotations, semantic Web usage mining, user modeling, ontologies and rules to adapt AJAX pages. The focus of our pater is the conceptual introduction of the autonomous client. An autonomous client directly executes all necessary adaptation steps based on a user model, without requesting any logic on the server. In order to realize this, we use ontologies to annotate Rich Internet Applications and to describe the user model as well as semantic Web usage mining for detecting adaptation rules. Additionally, we provide a detailed overview and evaluation of how we moved resource-intensive ontology processing and rules execution from the server to the client.".
- 90 abstract "In the semantic web environment, where two or more independent ontologies can be used in order to describe knowledge and data, ontologies have to be aligned by defining mappings among the elements of one ontology and the elements of another ontology. Very often, mappings are not derived by the semantics of the ontologies that are compared, but, rather, by an evaluation of the similarity of the terminology used in the two ontologies or of their syntactic structure. Moreover, ontology mappings can be inaccurate, because ontology matching tools derive such mappings from inaccurate terminology or even because they are not specifically tailored for the domain at hand. In this paper, we propose a new mapping validation approach for interpreting similarity-based mappings as semantic relations, by coping also with inaccuracy situations. The idea is to see two independent ontologies as a unique distributed knowledge base and to assume a semantic interpretation of ontology mappings as probabilistic and hypothetical relations among ontology elements. We present and use a probabilistic reasoning tool in order to validate mappings and to possibly infer new relations among the ontologies.".
- 1 abstract "Collaborative tagging systems have recently emerged as one of the rapidly growing web 2.0 applications. The informal social classification structure in these systems, also known as folksonomy, provides a convenient way to annotate resources by allowing users to use any keyword or tag that they find relevant. In turn, the flat and non-hierarchical structure with unsupervised vocabularies leads to low search precision and poor resource navigation and retrieval. This drawback has created the need for ontological structures, which provide shared vocabularies and semantic relations for translating and integrating the different sources. In this paper, we propose an integrated approach for extracting ontological structure from folksonomies that exploits the power of low support association rule mining supplemented by an upper ontology such as WordNet.".
- 101 abstract "Despite serious research efforts, automatic ontology matching still suffers from severe problems with respect to the quality of matching results. Existing matching systems trade-off precision and recall and have their specific strengths and weaknesses. This leads to problems when the right matcher for a given task has to be selected. In this paper, we present a method for improving matching results by not choosing a specific matcher but applying machine learning techniques on an ensemble of matchers. Hereby we learn rules for the correctness of a correspondence based on the output of different matchers and additional information about the nature of the elements to be matched, thus leveraging the weaknesses of an individual matcher. We show that our method always performs significantly better than the median of the matchers used and in most cases outperforms the best matcher with an optimal threshold for a given pair of ontologies. As a side product of our experiments, we discovered that the majority vote is a simple but powerful heuristic for combining matchers that almost reaches the quality of our learning results.".
- 104 abstract "In this paper we present a novel approach, called Concept Search, which extends syntactic search, i.e., search based on the computation of string similarity between words, with semantic search, i.e., search based on the computation of semantic relations among concepts. The key idea of Concept Search is to operate on complex concepts and to maximally exploit the semantic information available, reducing to syntactic search only when necessary, i.e., when no semantic information is available. The experimental results show that Concept Search performs at least as well as syntactic search, improving the quality of results as a function of the amount of available semantics.".
- 106 abstract "Semantic descriptions of knowledge acquisition (KA) tools and resources enable machine reasoning about KA systems and can be used to automate the discovery and composition of KA services, thereby increasing interoperability among systems and reducing system design and maintenance costs. Whilst there are a few general-purpose ontologies available that could be combined for describing knowledge acquisition, albeit at an inadequate abstraction level, there is as yet no KA ontology based on Semantic Web technologies available. In this paper, we present OAK, a well-founded, modular, extensible and multimedia-aware ontology of knowledge acquisition which extends existing foundational and core Semantic Web ontologies. We start by using a KA tool development scenario to illustrate the complexity of the problem, and identify a number of requirements for OAK. After we present the ontology in detail, we evaluate it with respect to the identified requirements.".
- 110 abstract "Semantic wikis extend wiki platforms with the ability to represent structured information in a machine-processable way. Ontop of the structured information in the wiki, novel ways to search, browse, and present the wiki content become possible. However, while powerful query languages offer new opportunities for semantic search, users typically are not willing to use the syntax of formal query languages. In this work we present an approach to semantic search that combines the expressiveness and capabilities of structured queries with the simplicity of keyword interfaces: Users articulate their information need using keyword queries, which are translated by the system into structured, conjunctive queries. This translation result may result in multiple possible interpretations of the information need, which can then be selected and further refined by the user via facets. We have implemented this approach to semantic search as an extension to Semantic MediaWiki. The results of a user study in the SMW-based community portal semanticweb.org show the efficiency and effectiveness of the approach.".
- 125 abstract "Building on our initial work on SAWSLD-MX, in this paper we extended the hybrid matchmaker by a structural approach utilizing the WSDL Analyzer tool, which performs structural, string-based and lexical comparison of WSDL 1.1 service descriptions and aims at supporting semi-automated Web service integration. A variant for aggregating results of different matching approaches using Support Vector Machines is presented. We report on the preliminary results of our performance evaluation of proposed aggregated SAWSDL matching vairants over the test collection SAWSDL-TC 1.".
- 127 abstract "Today a large amount of RDF data is published on the Web. However, the openness of the Web and the ease to combine RDF data from different sources creates new challenges. The Web of data is missing a uniform way to assess and to query the trustworthiness of information. In this paper we present tSPARQL, a trust-aware extension to SPARQL. Two additional keywords enable users to describe trust requirements and to query the trustworthiness of RDF data. Hence, tSPARQL allows adding trust to RDF-based applications in an easy manner. As the foundation we propose a trust model that associates RDF statements with trust values and we extend the SPARQL semantics to access these trust values in tSPARQL. Furthermore, we discuss opportunities to optimize the execution of tSPARQL queries.".
- 133 abstract "Ontologies are used to formally describe domains of interest. As domains change over time, the ontologies have to be updated accordingly. We advocate the introduction of an Ontology Update Language that captures frequent domain changes and hence facilitates regular updates to be made in ontologies. We thoroughly discuss the general design choices for defining such a language and a corresponding update framework. Moreover, we propose a concrete language proposal based on SPARQL Update and provide a reference implementation of the framework.".
- 142 abstract "A key aspect of semantic interoperability is the semantic mapping process itself. Traditionally, semantic mapping processes conducted by knowledge engineers have been proposed to bridge this gap. However, knowledge engineers alone are unlikely to cope with the ever increasing amount of mapping work required, especially as mappings themselves begin to be specialised for different contexts. One solution is to develop new mapping processes that enable users to participate in the mapping process themselves. In this paper we present an evaluation study of our user-driven tagging approach to the semantic mapping process. In our approach, users actively participate in generating mappings by categorising automatically generated candidate matches presented in natural language over a long time period. In the evaluation study three groups of users generated mappings between their personal ontologies and a sports ontology describing sports news content from RSS feeds. The mapping process was embedded within the users' work environment as a Firefox browser extension. The study is discussed, focusing on whether the mapping process is unintrusive, engaging and simplified for the user. The evaluation results were promising and indicate that people with various levels of expertise could become active in the semantic mapping process.".
- 143 abstract "Research in ontology learning from text has been mainly focused on entity recognition, taxonomy induction and relation extraction. In this work we approach a more challenging research issue, consisting in detecting semantic frames from texts, and using them to encode web ontologies. We exploit a new generation frame detection system, which is able to identify FrameNet frames and their argument boundaries from text parsing. In addition, we enrich frames with the results provided by a super-sense tagger, which extracts and classifies concepts and named entities from texts according to WordNet super-senses. The enrichment results include argument restrictions for the elements of a frame, and domain specializations, based on domain lexical unit detection for the target of a frame. The results are encoded according to the Lexical MetaModel, which allows a complete translation of lexical resources, keeps trace of the learning metadata, and enables custom transformations of enriched frames into modular ontology components, known as content ontology design patterns.".
- 147 abstract "Traditional ontology alignment techniques enable equivalence relationships to be established between concepts in two ontologies with some confidence value. With semantic matching, however, it is possible to identify not only equivalence relationships between concepts, but less general and more general relationships. This is beneficial since more expressive relationships can be discovered between ontologies thus helping us to resolve heterogeneity between differing semantic representations at a finer level of granularity. This work concerns the application of semantic matching to the medical domain. We have extended the SMatch algorithm to function in the medical domain with the use of the UMLS metathesaurus as the background resource, hence removing its previous reliance on WordNet, which does not cover the medical domain in a satisfactory manner. We describe the steps required to extend the SMatch algorithm to the medical domain for use with UMLS. We test the accuracy of our approach on subsets of the FMA and MeSH ontologies, with both precision and recall showing the accuracy and coverage of different versions of our algorithm on each dataset.".
- 15 abstract "In Semantic Web, the knowledge sources usually contain inconsistency because they are constantly changing and from different view points. As is well known, as based on the description logic of the Semantic Web, OWL is lack of the ability of tolerating inconsistent or incomplete data. Recently, the research in handling inconsistency in OWL becomes more and more important. In this paper, we present a paraconsistent OWL called quasi-classical OWL to handle inconsistency with holding important inference rules such as modus tollens, modus ponens, and disjunctive syllogism. We propose a terminable, sound and complete tableau algorithm to implement paraconsistent reasoning in quasi-classical OWL. In comparison with other approaches to handle inconsistency in OWL, our approach enhances the ability of reasoning by integrating paraconsistent reasoning with important classical inference rules.".
- 150 abstract "Search facilities are vital both within folksonomy (or social tagging mechanism) based systems and across folksonomy based systems. Although these systems allow great malleability and adaptability, they also surfer from problems, such as ambiguity in the meaning of tags, flat organisation of tags and some degree of unstabilising factor on consensus about which tags best describe some certain Web resources. It has been argued that folksonomy structure can be enhanced by ontologies; however, as suggested by Hotho et al., a key question remains open: how to exploit the benefits of ontologies without bothering untrained users with its rigidity. In this paper, we propose an approach to address the problem of ambiguity in tagging systems by expanding folksonomy search with ontologies, which is completely transparent to users. Preliminary implementations and evaluations on the efficiency and the usefulness of such expansions are very promising.".
- 151 abstract "There are many interesting Knowledge Representation questions surrounding rule languages for the Semantic Web. The most basic one is of course: which kind of rules should be used and how do they integrate with existing Description Logics? Similar questions have already been adressed in the field of Logic Programming, where one particular answer has been provided by the language of FO(ID). FO(ID) is an extension of classical first-order logic with a rule-based representation for inductive defintions. By offering a general integration of first-order logic and Logic Programs, it also induces a particular way of extending Description Logics with rules. The goal of this paper is to investigate this integration and discover whether there are interesting extensions of DL with rules that can be arrived at by imposing appropriate restrictions on the highly expressive FO(ID).".
- 159 abstract "While semantic similarity plays a crucial role for human categorization and reasoning, computational similarity measures have also been applied to fields such as semantics-based information retrieval or ontology engineering. Several measures have been developed to compare concepts specified in various description logics. In most cases, these measures are either structural or require a populated ontology. Structural measures fail with an increasing expressivity of the used description logic, while several ontologies, e.g., geographic feature type ontologies, are not populated at all. In this paper, we present an approach to reduce inter-concept to inter-instance similarity and thereby avoid the canonization problem of structural measures. The novel approach, called SIM-DL_A, reuses existing similarity functions such as co-occurrence or network measures from our previous SIM-DL measure. The required instances for comparison are derived from the completion tree of a slightly modified DL-tableau algorithm as used for satisfiability checking. Instead of trying to find one (clash-free) model, the tableau algorithm generates a set of proxy individuals used for comparison. The paper presents the algorithm, alignment matrix, and similarity functions as well as a detailed example.".
- 162 abstract "The Entity Name System is a service which aims at providing globally unique URIs for all kinds of real-world entities such as persons, locations and products, based on descriptions of these entities. Because entity descriptions available to the ENS for deciding on entity identity—Do two entity description refer to the same real-world entity?—are changing over time, the system sometimes has to revise its past decisions: One entity has been given two different URIs or two entities have been attributed the same URI. The question we have to investigate in this context is then: How do we propagate entity decision revisions to the clients, which make use of the URIs provided by the ENS? In this paper we propose a solution which relies on labelling the URIs with additional history information. These labels allows clients to locally detect deprecated URIs they are using and also merge IDs referring to the same real-world entity without needing to consult the ENS. Making update requests to the ENS for the detected URIs only considerably reduces the number of update requests, at the cost of a decrease in uniqueness quality. We investigate how much the number of update requests decreases using URI history labeling, as well as how this impacts the uniqueness of the URIs on the client. For the experiments we use both artificially generated entity revision histories as well as a real case study based on the revision history of the Dutch and Simple English Wikipedia.".
- 163 abstract "Many science archive centres publish very large volumes of image, simulation, and experiment data. In order to integrate and analyse the available data, scientists need to be able to (i) identify and locate all the data relevant to their work; (ii) understand the multiple heterogeneous data models in which the data is published; and (iii) interpret and process the data they retrieve. RDF has been shown to be a generally successful framework within which to perform such data integration work. It can be equally successful in the context of scientific data, if it is demonstrably practical to expose that data as RDF. In this paper we investigate the capabilities of RDF to enable the integration of scientific data sources. Specifically, we discuss the suitability of SPARQL for expressing scientific queries, and the performance of several triple stores and RDB2RDF tools for executing queries over a moderately sized sample of a large astronomical data set. We found that more research and improvements are required into SPARQL and RDB2RDF tools to efficiently expose existing science archives for data integration.".
- 180 abstract "We present a programmatic interface (SKOS API) and editor for working with the Simple Knowledge Organisation System SKOS. The SKOS API has been designed to work with SKOS models at a high level of abstraction to aid developers of applications that use SKOS. We describe a SKOS editor (SKOSEd) that is built on the Protege 4 framework using the OWL and SKOS API. As well as exploring the benefits of the principled extensibility afforded by this approach, we also explore the limitations placed upon SKOS by restricting SKOSEd to OWL-DL.".
- 181 abstract "We consider the problem of tag prediction in collaborative tagging systems where users share and annotate resources on the Web. We put forward HAMLET, a novel approach to automatically propagate tags along the edges of a graph which relates similar documents. We identify the core principles underlying tag propagation for which we derive suitable scoring models combined in one overall ranking formula. Leveraging these scores, we present an efficient top-k tag selection algorithm that infers additional tags by carefully inspecting neighbors in the document graph. Experiments using real-world data demonstrate the viability of our approach in large-scale environments where tags are scarce.".
- 186 abstract "We present a platform for semantic medical image annotation and retrieval. It leverages on the MEDICO ontology which covers formal background information from various biomedical ontologies such as the Foundational Model of Anatomy (FMA), terminologies like ICD10 and RadLex and covers various aspects of clinical procedures. This ontology is used during several steps of annotation and retrieval: (1) We developed an ontology-driven metadata extractor for the medical image format DICOM. Its output contains, e.g., person name, age, image acquisition parameters, body region etc. (2) The output from (1) is used to simplify the manual annotation by providing intuitive visualizations and to provide a preselected subset of annotation concepts. Furthermore, the extracted metadata is linked together with anatomical annotations and clinical findings to generate a unified view on a patient's medical history. (3) On the search side we perform query expansion based on the structure of the medical ontologies. (4) Our ontology for clinical data management allows to link and combine patients, medical images and annotations together in a comprehensive result list. (5) The medical annotations are further extended by links to external sources like Wikipedia to provide additional information.".
- 192 abstract "We describe the design and use of the Ontology Pre-Processor Language (OPPL) as a means of embedding the use of Knowledge Patterns in OWL ontologies. Patterns provide a means of addressing the opacity and sustainability of OWL ontologies. We illustrate the specification of patterns in OPPL and discuss the advantages of its adoption by Ontology Engineers with respect to ontology generation, transformation, and maintainability. The consequence of the declarative specification of patterns will be their unambiguous description inside an ontology in OWL. Thus, OPPL enables an ontology engineer to work at the level of the pattern, rather than of the raw OWL axioms. Moreover, patterns can be analysed formally, so that the repercussions of their re-use can be better understood by ontology engineers and tools implementers.".
- 198 abstract "Person disambiguation monitors web appearances of a person by disambiguating information belonging to different people sharing the same name. In this paper we extend person disambiguation to incorporate the abstract notion of identity. This extension utilises semantic web technologies to represent the identity of the person to be found and the web resources to be disambiguated as semantic graphs. Our approach extracts a complete semantic social graph from distributed web 2.0 services. Web resources containing possible person references are converted into semantic graphs describing available identity features. We disambiguate these web resources to identify correct identity references by performing random walks through the graph space, measuring the distances between the social graph and web resource graphs, and clustering similar web resources. We present a new distance measure called “Optimum Transitions” and evaluate the accuracy of our approach using the information retrieval measure f-measure.".
- 201 abstract "In this paper we present Semanta – a fully-implemented system supporting Semantic Email Processes, integrated into the existing technical landscape and using existing email transport technology. By applying Speech Act Theory, knowledge about these processes can be made explicit, enabling machines to support email users with correctly interpreting, handling and keeping track of email messages, visualizing email threads and workflows, and extracting tasks and appointments from email messages. Whereas complex theoretical models and semantics are hidden beneath a simplistic user interface, the enabled functionalities are clear for the users to see and take advantage of. The system’s evaluation proved that our experiment with Semanta has indeed been successful and that semantic technology can be applied as an extra layer to existing technology, thus bringing its benefits into everyday computer usage.".
- 203 abstract "The increasing number of functionally similar services requires the existence of a non-functional properties selection process based on the Quality of Service (QoS). Thus, in this article authors focus on the provision of a QoS model, an architecture and an implementation which enhance the selection process by the annotation of Service Level Agreement (SLA) templates with semantic QoS metrics. This QoS model is composed by a specification for annotating SLA templates files, a QoS conceptual model formed as a QoS ontology and selection algorithm. This approach, which is background compatible, provides interoperability among customer-providers and lightweight alternative. Finally, its applicability and benefits are shown by using examples of Infrastructure services.".
- 205 abstract "Recent years have seen the utilisation of Semantic Web Service descriptions for automating a wide range of service-related activities, with a primary focus on service discovery, composition, execution and mediation. An important area which so far has received less attention is service validation, whereby advertised services are proven to conform to required behavioural specifications. This paper proposes a method for validation of service-oriented systems through automated functional testing. The method leverages ontology-based and rule-based descriptions of service inputs, outputs, preconditions and effects (IOPE) for constructing a stateful EFSM specification. The specification is subsequently utilised for functional testing and validation using the proven Stream X-machine (SXM) testing methodology. Complete functional test sets are generated automatically at an abstract level and are then applied to concrete Web services, using test drivers created from the Web service descriptions. The testing method comes with completeness guarantees and provides a strong method for validating the behaviour of Web services.".
- 218 abstract "Many applications operate on time-“sensitive” data. Some of these data are only valid for certain intervals (e.g., job-assignments, versions of software code), others describe temporal events that happened at certain points in time (e.g., a person’s birthday). Until recently, the only way to incorporate time into Semantic Web models was as a data type property. Temporal RDF, however, considers time as an additional dimension in data preserving the semantics of time. In this paper we present a syntax and storage format based on named graphs to express temporal RDF. Given the restriction to preexisting RDF-syntax, our approach can perform any temporal query using standard SPARQL syntax only. For convenience, we introduce a shorthand format called T-SPARQL for temporal queries and show how T-SPARQL queries can be translated to standard SPARQL. Additionally, we show that, depending on the underlying data's nature, the temporal RDF approach vastly reduces the number of triples by eliminating redundancies resulting in an increased performance for processing and querying. Last but not least, we introduce a new indexing approach method that can significantly reduce the time needed to execute time point queries (e.g., what happened on January 1st).".
- 219 abstract "The increasing adoption of semantic web technology in application scenarios with frequently changing data has imposed new requirements on the underlying tools. Reasoning algorithms need to be optimized for the processing of dynamic knowledge bases and semantic frameworks have to provide novel mechanisms for detecting changes of knowledge. Today, the latter is mostly realized by implementing simple polling mechanisms. However, this implies client-side post-processing of the received results, causes high response times and limits the overall throughput of the system. In this paper, we present a heuristics framework for realizing a subscription mechanism for dynamic knowledge bases. By analyzing similarities between published information and resulting notifications, heuristics can be employed to “guess” subsequent notifications. As testing the correctness of guessed notifications can be implemented efficiently, notifications can be delivered to the subscribers in an earlier processing phase and the system throughput can be increased. We experimentally evaluate our approach based on a concrete application scenario.".
- 22 abstract "We propose a general method and novel algorithmic techniques to facilitate the integration of independently developed ontologies using mappings. Our method and techniques aim at helping users understand and evaluate the semantic consequences of the integration, as well as to detect and fix potential errors. We also present a system that implements our approach, and a preliminary evaluation which suggests that our approach is both useful and feasible in practice.".
- 222 abstract "Finding the optimal selection of an OWL reasoner and service interface for a specific ontology-based application is challenging. Matching application requirements with service offerings from available reasoning engines has become more and more difficult over time with recent optimizations for certain reasoning services and new reasoning algorithms for different fragments of OWL. This work is largely motivated by real-world experiences and will report about interesting findings in the course of developing an ontology-based application. Benchmarking outcomes of several reasoning engines are discussed - especially with respect to accompanying sound and completeness tests. Furthermore we give an account of issues and a performance comparison with respect to various service and communication protocols which show that this largely neglected component may have an enormous impact on the overall performance.".
- 225 abstract "More and more applications use the RDF framework as their data model and RDF stores to index and retrieve their data. Many of these applications require both structured queries as well as fulltext search. SPARQL addresses the first requirement in a standardized way, while fulltext search is provided by store-specific implementations. RDF benchmarks enable developers to compare structured query performance of different stores, but for fulltext search on RDF data no such benchmarks and comparisons exist so far. In this paper, we extend the LUBM benchmark with synthetic scalable fulltext data and corresponding queries for fulltext-related query performance evaluation. Based on the extended benchmark, we provide a detailed comparison of fulltext search features and performance of the most widely used RDF stores. Results show interesting RDF store insights for basic fulltext queries (classic IR queries) as well as hybrid queries (structured and fulltext queries). Our results are not only valuable for selecting the right RDF store for specific applications, but also reveal the need for performance improvements for certain kinds of queries.".
- 227 abstract "A number of projects (myGrid, BioMOBY, etc.) have been initiated to organise emerging bioinformatics Web Services and provide their semantic descriptions. They typically rely on manual curation efforts. In this paper we focus on a semi-automated approach to mine semantic descriptions from the bioinformatics literature. The method combines terminological processing and dependency parsing of journal articles, and applies information extraction techniques to profile Web services using informative textual passages, related ontological annotations and service descriptors. Service descriptors are terminological phrases reflecting specific roles (e.g. input, output, etc.) of the related semantic classes (e.g. algorithm, database, etc.). They can be used to facilitate subsequent manual description of services, but also for providing a semantic synopsis of a service that can be used to locate related services. We present a case-study involving a subset of full text articles from the BMC Bioinformatics journal. We illustrate the potential of natural language processing not only for mining descriptions of known services, but also for discovering new services that have been described in the literature.".
- 230 abstract "We consider the problem of a user querying semistructured data such as RDF without knowing its structure. In these circumstances, it is helpful if the querying system can perform an approximate matching of the user's query to the data and can rank the answers in terms of how closely they match the original query. We show that our approximate matching framework allows us to incorporate RDFS inference rules as well as standard notions of approximation such as edit distance, thereby capturing semantic as well as syntactic approximations. The query language we adopt comprises conjunctions of regular path queries, thus including extensions proposed for SPARQL to allow for querying paths using regular expressions. We provide an incremental query evaluation algorithm which runs in polynomial time and returns answers to the user in ranked order.".
- 232 abstract "As \emph{social networks} are becoming ubiquitous on the Web, the Semantic Web goals indicate that it is critical to have a standard model allowing exchange, interoperability, transformation, and querying of social network data. In this paper we show that RDF/SPARQL meet this \emph{desiderata}. Building on developments of {\em social network analysis}, {\em graph databases} and {\em Semantic Web}, we present a social networks data model based on RDF, and a query and transformation language based on SPARQL meeting the above requirements. We study its expressive power and complexity showing that it behaves well, and present an illustrative prototype.".
- 234 abstract "The primary goal of the Semantic Web is to use URIs as a universal space to name anything, expanding from using URIs for webpages to URIs for “real ob jects and imaginary concepts” as put by Berners-Lee. This distinction has often been tied to the distinction between information resources, like webpages and multimedia files, and non-information resources, which are everything from real-people and bound books. Furthermore, the W3C has recommended not to use the same URI for information resources and non-information resources, and several communities like the Linked Data initiative are deploying this principle. Yet, the definition put forward by the W3C, that non-information resources are things whose “essential nature is information” seems confusing at best. For example, would the text of Moby Dick be an information resource? While this problem could safely be ignored up till now as a mere distraction, with both the rise of Linked Data, projects like OKKAM, and recent work on modelling HTTP in RDF for error reports, it appears that this problem must be modelled formally. An ontology called IRW (Identity and Reference on the Web) of various types of resources and their relationships, both for the hypertext Web and the Semantic Web, is presented. It builds upon Information Object Lite (an extension of DOLCE Ultra Lite for describing information objects) and IRE and aligns with the work of the W3C in modelling HTTP in RDF and Berners-Lee’s Tabulator ontology. It can be used as a tool to make the Semantic Web more self-describing, and it also allows inference to be used to test for membership in various classes of resource, and so for validating Linked Data.".
- 27 abstract "In order to overcome the limitations of the purely deductive approaches to query answering from ontologies, inductive (instance-based) methods have been proposed as efficient and noise-tolerant tools. In this paper we propose an original approach based on non-parametric learning: the Reduced Coulomb Energy Network classifier. The method requires a limited training effort (more than nearest neighbor yet less than kernel machines) but can turn out to be very effective in the classification phase. Casting retrieval as the problem of assessing class-memberships w.r.t. the query concepts, we propose an extension of a classification algorithm using a Reduced Coulomb Energy Network based on an entropic similarity measure for OWL. Experimentally we show that the behavior of the classifier is comparable with the one of a standard reasoner and is often more efficient than with other inductive approaches. Moreover we show that new knowledge (not logically derivable) is induced.".
- 33 abstract "Open Answer Set Programming (OASP) is an attractive framework for integrating ontologies and rules. Although several decidable fragments of OASP have been identified, few reasoning procedures exist. In this paper, we provide a sound, complete, and terminating algorithm for satisfiability checking w.r.t. forest logic programs, a fragment where rules have a tree shape and allow for inequality atoms and constants. We further introduce f-hybrid knowledge bases, a hybrid framework where SHOQ knowledge bases and forest logic programs co-exist, and we show that reasoning with such knowledge bases can be reduced to reasoning with forest logic programs only. We note that f-hybrid knowledge bases do not require the usual (weakly) DL-safety of the rule component, providing thus a genuine alternative approach to hybrid reasoning.".
- 34 abstract "We propose an automatic system for annotating accurately data tables extracted from the web. This system is designed to provide additional data to an existing querying system called MIEL, which relies on a common vocabulary used to query local relational databases. We will use the same vocabulary, translated into an OWL ontology, to annotate the tables. Our annotation system is unsupervised. It uses only the knowledge defined in the ontology to automatically annotate the entire content of tables, using an aggregation approach: first annotate cells, then columns, then relations between those columns. The annotations are fuzzy: instead of linking an element of the table with a precise concept of the ontology, the elements of the table are annotated with several concepts, associated with their relevance degree. Our annotation process has been validated experimentally on scientific domains (microbial risk in food, chemical risk in food) and a technical domain (aeronautics).".
- 39 abstract "In this paper we argue why it is necessary to associate linguistic information with ontologies and why more expressive models, beyond RDFS, OWL and SKOS, are needed to capture the relation between natural language constructs on the one hand and ontological entities on the other. We argue that in the light of tasks such as ontology-based information extraction, ontology learning and population from text and natural language generation from ontologies, currently available datamodels are not sufficient as they only allow to associate atomic terms without linguistic grounding or structure to ontology elements. Towards realizing a more expressive model for associating linguistic information to ontology elements, we base our work presented here on previously developed models (LingInfo, LexOnto, LMF) and present a new joint model for linguistic grounding of ontologies called LexInfo. LexInfo combines essential design aspects of LingInfo and LexOnto and builds on a sound model for representing computational lexica called LMF which has been recently approved as a standard under ISO.".
- 44 abstract "This paper investigates a Description Logic, namely $\mathcal{SHI}_+$, which extends $\mathcal{SHI}$ by adding transitive closure of roles. The resulting logic $\mathcal{SHI}_+$ allows transitive closure of roles to occur not only in concept inclusion axioms but also in role inclusion axioms. We show that $\mathcal{SHI}_+$ is decidable by devising a sound and complete algorithm for deciding satisfiability of concepts in $\mathcal{SHI}_+$ with respect to a set of concept and role inclusion axioms.".