Sebastian Rudolph

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Exercise 8.1. Transform the following concepts into negation normal form: (a) ¬(A u ∀r.B) (b) ¬∀r.∃s.(¬B t ∃r.A) (c) ¬((¬A u ∃r.>) t> 3 s.(A t ¬B)) Exercise 8.2. Apply the tableau algorithm in order to check if the axiom A v B is a logical consequence of the TBox {¬C v B,A u C v ⊥}. Exercise 8.3. Aply the tableau algorithm in order to check satisfiability(More)
Streams of events appear increasingly today in various Web applications such as blogs, feeds, sensor data streams, geospatial information, on-line financial data, etc. Event Processing (EP) is concerned with timely detection of compound events within streams of simple events. State-of-the-art EP provides on-the-fly analysis of event streams, but cannot(More)
Keyword queries enjoy widespread usage as they represent an intuitive way of specifying information needs. Recently, answering keyword queries on graph-structured data has emerged as an important research topic. The prevalent approaches build on dedicated indexing techniques as well as search algorithms aiming at finding substructures that connect the data(More)
Current information retrieval (IR) approaches do not formally capture the explicit meaning of a keyword query but provide a comfortable way for the user to specify information needs on the basis of keywords. Ontology-based approaches allow for sophisticated semantic search but impose a query syntax more difficult to handle. In this paper, we present an(More)
Complex Event Processing (CEP) is concerned with timely detection of complex events within multiple streams of atomic occurrences. It has useful applications in areas including financial services, mobile and sensor devices, click stream analysis etc. Numerous approaches in CEP have already been proposed in the literature. Event processing systems with a(More)
We introduce ELP as a decidable fragment of the Semantic Web Rule Language (SWRL) that admits reasoning in polynomial time. ELP is based on the tractable description logic EL, and encompasses an extended notion of the recently proposed DL rules for that logic. Thus ELP extends EL with a number of features introduced by the forthcoming OWL 2, such as(More)
Addressing the dynamics and notification in the Semantic Web realm has recently become an important area of research. Run time data is generated by multiple social networks, sensor networks, various on-line services, and so on. The challenge is how to get advantage of a huge amount of real time data, i.e., how to integrate heterogeneous data streams,(More)
Horn fragments of Description Logics (DLs) have gained popularity because they provide a beneficial trade-off between expressive power and computational complexity and, more specifically, are usually tractable w.r.t. data complexity. Despite their potential, and partly due to the intricate interaction of nominals (O), inverses (I) and counting (Q), such(More)
The automated extraction of information from text and its transformation into a formal description is an important goal in both Semantic Web research and computational linguistics. The extracted information can be used for a variety of tasks such as ontology generation, question answering and information retrieval. LODifier is an approach that combines deep(More)
Description logics (DLs) have become a prominent paradigm for representing knowledge in a variety of application areas, partly due to their ability to achieve a favourable balance between expressivity of the logic and performance of reasoning. Horn description logics are obtained, roughly speaking, by disallowing all forms of disjunctions. They have(More)