In this paper we take a view from the bottom to RDF(S) reasoning. We discuss some issues and requirements on reasoning towards effectively building Semantic Web Pipes, aggregating RDF data from various distributed sources. If we leave out complex description logics reasoning and restrict ourselves to the RDF world, it turns out that some problems, in particular how to deal with contradicting RD...

The WebID protocol solves the challenge of remembering usernames and passwords. We enhance this protocol in three ways. First, we give it the ability to manage groups of agents and control their access to resources on the Web. Second, we add support for biometric access control to enhance security. Finally, we add support for OWL-based policies that may be federated and result in flexible acces...

We consider social peer-to-peer data management systems (PDMS), where each peer maintains both semantic mappings between its schema and some acquaintances, and social links with peer friends. In this context, reformulating a query from a peer’s schema into other peer’s schemas is a hard problem, as it may generate as many rewritings as the set of mappings from that peer to the outside and trans...

The vast majority of applications consider generic notion of trust of a person to others, which is not restricted to any particular context or situation. Motivated by the financial scenario consuming data from distributed sources on the Web, we argue that we (as information consumers) cannot trust the information publishers or authors in general, however, only regarding the particular topics of...

This paper proposes integration of a social network with the tripartite model of ontologies by P. Mika. That model is based on three dimensions, i.e. actors, concepts and instances, and illustrates ontology emergence using actor-concept and conceptinstance relations. However, another important ingredient is the actor-actor relation. For example, a vocabulary is sometimes shared within a communi...

The paper presents a visual notation for the Web Ontology Language (OWL) providing an integrated view on the classes and individuals of ontologies. The classes are displayed as circles, with the size of each circle representing its connectivity in the ontology. The individuals are represented as sections in the circles so that it is immediately clear from the visualization how many individuals ...

Lightweight ontologies in the form of RDF vocabularies such as SIOC, FOAF, vCard, etc. are increasingly being used and exported by “serious” applications recently. Such vocabularies, together with query languages like SPARQL also allow to syndicate resulting RDF data from arbitrary Web sources and open the path to finally bringing the Semantic Web to operation mode. Considering, however, that m...

We propose P2Prec, a P2P recommendation system for large-scale data sharing, which exploits friendship links. The main idea is to recommend high quality contents related to query topics and contents of friends (or friends of friends), who are expert on the topics related to the query. Expertise is implicitly deduced based on the contents stored by a user. To exploit friendship links, we rely on...

Community portals such as blogs, wikis and photo sharing sites have become the new channels for information dissemination on the Web. When searching for information, many results end up in some type of community site. However, one cannot make use of the wealth of information that is available through the preferences of one's thematic social network, or through bookmarks or other documents, only...

The semantic web ontology languages RDFS and OWL are widely used but limited in both their expressivity and their support for modularity and integrated documentation. Expressivity, modularity, and documentation of formal knowledge have always been important issues in the MKM community. Therefore, we try to improve these ontology languages by well-tried MKM techniques. Concretely, we propose emb...