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In this paper, we consider an approach to update nonmonotonic knowledge bases represented as extended logic programs under the answer set semantics. In this approach, new information is incorporated into the current knowledge base subject to a causal rejection principle, which enforces that, in case of conflicts between rules, more recent rules are… (More)

Motivation ® The study of equivalence relations and equivalence classes of mathematical structures is a fundamental concept in algebra. ® In CS, semantic comparisons of theories and programs, like different notions of equivalence, are of practical interest, • for program optimization tasks; • for program verification tasks; • for concepts of modular… (More)

Many data integration systems provide transparent access to heterogeneous data sources through a unified view of all data in terms of a global schema, which may be equipped with integrity constraints on the data. Since these constraints might be violated by the data retrieved from the sources, methods for handling such a situation are needed. To this end,… (More)

We provide two approaches for explaining inconsistency in multi-context systems, where decentralized and heterogeneous system parts interact via nonmonotonic bridge rules. Inconsistencies arise easily in such scenarios, and nonmono-tonicity calls for specific methods of inconsistency analysis. Both our approaches characterize inconsistency in terms of… (More)

Multi-context systems (MCS) are a powerful framework for interlinking heterogeneous knowledge sources. They model the flow of information among different reasoning components (called contexts) in a declarative way, using so-called bridge rules, where contexts and bridge rules may be nonmono-tonic. We considerably generalize MCS to managed MCS (mMCS): while… (More)

We consider the simplification of logic programs under the stable-model semantics, with respect to the notions of strong and uniform equivalence between logic programs, respectively. Both notions have recently been considered for nonmonotonic logic programs (the latter dates back to the 1980s, though) and provide semantic foundations for optimizing programs… (More)

Linked Stream Data, i.e., the RDF data model extended for representing stream data generated from sensors social network applications, is gaining popularity. This has motivated considerable work on developing corresponding data models associated with processing engines. However, current implemented engines have not been thoroughly evaluated to assess their… (More)

Among others, Alferes et al. (1998) presented an approach for updating logic programs with sets of rules based on dynamic logic programs. We syntactically redefine dynamic logic programs and investigate their semantical properties, looking at them from perspectives such as a belief revision and abstract consequence relation view. Since the approach does not… (More)

Answer set programming is a declarative programming paradigm rooted in logic programming and non-monotonic reasoning. This formalism has become a host for expressing knowledge representation problems, which reinforces the interest in efficient methods for computing answer sets of a logic program. The complexity of various reasoning tasks for general answer… (More)

The recent rise of smart applications has drawn interest to logical reasoning over data streams. Different query languages and stream processing/reasoning engines were proposed. However, due to a lack of theoretical foundations, the expressivity and semantics of these diverse approaches were only informally discussed. Towards clear specifications and means… (More)