Simon Schenk

Networked graphs: a declarative mechanism for SPARQL rules, SPARQL views and RDF data integration on the web

Easy reuse and integration of declaratively described information in a distributed setting is one of the main motivations for building the Semantic Web. Despite of this claim, reuse and recombination of RDF data today is mostly done using data replication and procedural code. A simple declarative mechanism for reusing and combining RDF data would help users to generate content for the semantic web. Having such a mechanism, the Semantic Web could better benefit from user generated content, as it is broadly present in the so called Web 2.0, but also from better linkage of existing content. We propose Networked Graphs, which allow users to define RDF graphs both, by extensionally listing content, but also by using views on other graphs. These views can be used to include parts of other graphs, to transform data before including it and to denote rules. The relationships between graphs are described declaratively using SPARQL queries and an extension of the SPARQL semantics. Networked Graphs are easily exchangeable between and interpretable on different computers. Using existing protocols, Networked Graphss can be evaluated in a distributed setting.

Semantic Multimedia

Multimedia constitutes an interesting field of application for Semantic Web and Semantic Web reasoning, as the access and management of multimedia content and context depends strongly on the semantic descriptions of both. At the same time, multimedia resources constitute complex objects, the descriptions of which are involved and require the foundation on sound modeling practice in order to represent findings of low- and high level multimedia analysis and to make them accessible via Semantic Web querying of resources. This tutorial aims to provide a red thread through these different issues and to give an outline of where Semantic Web modeling and reasoning needs to further contribute to the area of semantic multimedia for the fruitful interaction between these two fields of computer science.

SemaPlorer-Interactive semantic exploration of data and media based on a federated cloud infrastructure

SemaPlorer is an easy to use application that allows end users to interactively explore and visualize a very large, mixed-quality and semantically heterogeneous distributed semantic data set in real-time. Its purpose is to acquaint oneself about a city, touristic area, or other area a user is interested in. By visualizing the data using a map, media, and different context views, SemaPlorer advances beyond simple storage and retrieval of large numbers of triples, as the interaction with the large data set is driven by the user. SemaPlorer leverages different semantic data sources such as DBpedia, GeoNames, WordNet, and personal FOAF files. These make a significant portion of the data provided for the Billion Triple Challenge. SemaPlorer intriguingly connects with a large Flickr data set converted to RDF. The storage infrastructure bases on Amazons Elastic Computing Cloud (EC2) and Simple Storage Service. We apply NetworkedGraphs as a conceptual layer on top of EC2, realizing a large, federated data infrastructure for semantically heterogeneous data sources from within and outside of the cloud. Therefore, the application is scalable with respect to the amount of distributed components working together as well as the number of triples managed overall. Hence, SemaPlorer is flexible enough to leverage for exploration of almost arbitrary additional data sources that might be added in the future. We conducted a formative evaluation of the SemaPlorer application with 20 test subjects. The results of this evaluation are analyzed and their implication to future work discussed. SemaPlorer won the first prize at the Billion Triple Challenge of the International Semantic Web Conference in Karlsruhe, 2008.

Model Driven Specification of Ontology Translations

The alignment of different ontologies requires the specification, representation and execution of translation rules. The rules need to integrate translations at the lexical, the syntactic and the semantic layer requiring semantic reasoning as well as low-level specification of ad-hoc conversions of data. Existing formalisms for representing translation rules cannot cover the representation needs of these three layers in one model. We propose a metamodel-based representation of ontology alignments that integrate semantic translations using description logics and lower level translation specifications into one model of representation for ontology alignments.

On the Semantics of Trust and Caching in the Semantic Web

The Semantic Web is a distributed environment for knowledge representation and reasoning. The distributed nature brings with it failing data sources and inconsistencies between autonomous knowledge bases. To reduce problems resulting from unavailable sources and to improve performance, caching can be used. Caches, however, raise new problems of imprecise or outdated information. We propose to distinguish between certain and cached information when reasoning on the semantic web, by extending the well known

Lifecycle knowledge management: getting the semantics across in X-media

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Introducing social aspects to search in peer-to-peer networks

bilattice of truth and knowledge orders to

Linked Open Data für die Exploration von Wissen im Web 2.0 mit SemaPlorer

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Interaktive Exploration und Visualisierung von semantischem Wissen mit SemaPlorer (Interactive Exploration and Visualization of Semantic Knowledge with SemaPlorer).

, taking into account cached information. We discuss how users can be offered additional information about the reliability of inferred information, based on the availability of the corresponding information sources. We then extend the framework towards

TagFS | Tag Semantics for Hierarchical File Systems

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