Early nested word automata for XPath query answering on XML streams

To reason with existential rules (a.k.a. tuple-generating dependencies), one often computes universal models. Among the many such models of different structure and cardinality, the core is arguably the “best”. Especially for finitely satisfiable theories, where the core is the unique smallest universal model, it has advantages in query answering, non-monotonic reasoning, and data exchange. Unfortunately, computing cores is difficult and not supported by most reasoners. We therefore propose ways of computing cores using practically implemented methods from rule reasoning and answer set programming. Our focus is on cases where the standard chase algorithm produces a core. We characterise this desirable situation in general terms that apply to a large class of cores, derive concrete approaches for decidable special cases, and generalise these approaches to non-monotonic extensions of existential rules.

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Benchmarking Approximate Consistent Query Answering

Proceedings of the 40th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems ◽

10.1145/3452021.3458309 ◽

2021 ◽

Author(s):

Marco Calautti ◽

Marco Console ◽

Andreas Pieris

Keyword(s):

Query Answering ◽

Consistent Query Answering

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An Improved Set-based Reasoner for the Description Logic 𝒟ℒD4,×†

Fundamenta Informaticae ◽

10.3233/fi-2021-2009 ◽

2021 ◽

Vol 178 (4) ◽

pp. 315-346

Author(s):

Domenico Cantone ◽

Marianna Nicolosi-Asmundo ◽

Daniele Francesco Santamaria

Keyword(s):

Semantic Web ◽

Set Theory ◽

Description Logic ◽

Knowledge Bases ◽

Query Answering ◽

Conjunctive Query ◽

Classification Problems ◽

Previous Version ◽

Decidable Fragment ◽

Stratified Set

We present a KE-tableau-based implementation of a reasoner for a decidable fragment of (stratified) set theory expressing the description logic 𝒟ℒ〈4LQSR,×〉(D) (𝒟ℒD4,×, for short). Our application solves the main TBox and ABox reasoning problems for 𝒟ℒD4,×. In particular, it solves the consistency and the classification problems for 𝒟ℒD4,×-knowledge bases represented in set-theoretic terms, and a generalization of the Conjunctive Query Answering problem in which conjunctive queries with variables of three sorts are admitted. The reasoner, which extends and improves a previous version, is implemented in C++. It supports 𝒟ℒD4,×-knowledge bases serialized in the OWL/XML format and it admits also rules expressed in SWRL (Semantic Web Rule Language).

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