1,721,187 research outputs found
Polynomial conjunctive query rewriting under unary inclusion dependencies
Full text linkOntology-based data access (OBDA) is widely accepted as an important ingredient of the new generation of information systems. In the OBDA paradigm, potentially incomplete relational data is enriched by means of ontologies, representing intensional knowledge of the application domain. We consider the problem of conjunctive query answering in OBDA. Certain ontology languages have been identified as FO-rewritable (e.g., DL-Lite and sticky-join sets of TGDs), which means that the ontology can be incorporated into the user's query, thus reducing OBDA to standard relational query evaluation. However, all known query rewriting techniques produce queries that are exponentially large in the size of the user's query, which can be a serious issue for standard relational database engines. In this paper, we present a polynomial query rewriting for conjunctive queries under unary inclusion dependencies. On
the other hand, we show that binary inclusion dependencies do not admit
polynomial query rewriting algorithms
Unsupervised author identification and characterization
No full textAuthor identification is a hot topic, especially in the Internet age. Following our previous work in which we proposed a novel approach to this problem, based on relational representations that take into account the structure of sentences, here we present a tool that computes and visualizes a numerical and graphical characterization of the authors/texts based on several linguistic features. This tool, that extends a previous language analysis tool, is the ideal complement to the author identification technique, that is based on a clustering procedure whose outcomes (i.e., the authors’ models) are not human-readable. Both approaches are unsupervised, which allows them to tackle problems to which other state-of-the-art systems are not applicable
Preaface to the "3rd International Workshop on Data Meets Applied Ontologies in Explainable AI, DAO-XAI 2021"
No full textReasoning in Expressive Description Logics with Fixpoints based on Automata on Infinite Trees.
No full textTowards Implementing Finite Model Reasoning in Description Logics
No full textCEUR Workshop Proceeding
Verification and monitoring for first-order LTL with persistence-preserving quantification over finite and infinite traces
Full text linkWe address the problem of model checking first-order dynamic systems where new objects can be injected in the active domain during execution. Notable examples are systems induced by a first-order action theory expressed, e.g., in the situation calculus. Recent results show that, under state-boundedness, such systems, in spite of having a first-order representation of the state, admit decidable model checking for full first-order mu-calculus. However, interestingly, model checking remains undecidable in the case of first-order LTL (LTL-FO). In this paper, we show that in LTL-FOp, the fragment of LTL-FO where quantification ranges only over objects that persist along traces, model checking state-bounded systems becomes decidable over infinite and finite traces. We then employ this result to show how to handle monitoring of LTL-FOp properties against a trace stemming from an unknown state-bounded dynamic system, simultaneously considering the finite trace up to the current point, and all its possibly infinite future continuations
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