Search Results for author: Michael Zakharyaschev

Found 9 papers, 0 papers with code

A tetrachotomy of ontology-mediated queries with a covering axiom

no code implementations7 Jun 2020 Olga Gerasimova, Stanislav Kikot, Agi Kurucz, Vladimir Podolskii, Michael Zakharyaschev

In this article, aiming to understand the fundamental roots of this difficulty, we strip the problem to the bare bones and focus on Boolean conjunctive queries mediated by a simple covering axiom stating that one class is covered by the union of two other classes.

Data Complexity and Rewritability of Ontology-Mediated Queries in Metric Temporal Logic under the Event-Based Semantics (Full Version)

no code implementations30 May 2019 Vladislav Ryzhikov, Przemyslaw Andrzej Walega, Michael Zakharyaschev

We investigate the data complexity of answering queries mediated by metric temporal logic ontologies under the event-based semantics assuming that data instances are finite timed words timestamped with binary fractions.

Query Inseparability for ALC Ontologies

no code implementations31 Jan 2019 Elena Botoeva, Carsten Lutz, Vladislav Ryzhikov, Frank Wolter, Michael Zakharyaschev

We also consider the problem whether two ALC TBoxes give the same answers to any query over any ABox in a given signature and show that, for CQs, this problem is undecidable, too.

Inseparability and Conservative Extensions of Description Logic Ontologies: A Survey

no code implementations20 Apr 2018 Elena Botoeva, Boris Konev, Carsten Lutz, Vladislav Ryzhikov, Frank Wolter, Michael Zakharyaschev

The question whether an ontology can safely be replaced by another, possibly simpler, one is fundamental for many ontology engineering and maintenance tasks.

Ontology-Mediated Queries: Combined Complexity and Succinctness of Rewritings via Circuit Complexity

no code implementations4 May 2016 Meghyn Bienvenu, Stanislav Kikot, Roman Kontchakov, Vladimir Podolskii, Michael Zakharyaschev

We give solutions to two fundamental computational problems in ontology-based data access with the W3C standard ontology language OWL 2 QL: the succinctness problem for first-order rewritings of ontology-mediated queries (OMQs), and the complexity problem for OMQ answering.

Query-Based Entailment and Inseparability for ALC Ontologies (Full Version)

no code implementations14 Apr 2016 Elena Botoeva, Carsten Lutz, Vladislav Ryzhikov, Frank Wolter, Michael Zakharyaschev

We also consider the problem whether two ALC TBoxes give the same answers to any query in a given vocabulary over all ABoxes, and show that for CQs this problem is undecidable, too, but becomes decidable and 2EXPTIME-complete in Horn-ALC, and even EXPTIME-complete in Horn-ALC when restricted to (unions of) rooted CQs.

Logic in Computer Science

The DL-Lite Family and Relations

no code implementations15 Jan 2014 Alessandro Artale, Diego Calvanese, Roman Kontchakov, Michael Zakharyaschev

The recently introduced series of description logics under the common moniker DL-Lite has attracted attention of the description logic and semantic web communities due to the low computational complexity of inference, on the one hand, and the ability to represent conceptual modeling formalisms, on the other.

Temporal Description Logic for Ontology-Based Data Access (Extended Version)

no code implementations18 Apr 2013 Alessandro Artale, Roman Kontchakov, Frank Wolter, Michael Zakharyaschev

Our aim is to investigate ontology-based data access over temporal data with validity time and ontologies capable of temporal conceptual modelling.

A Cookbook for Temporal Conceptual Data Modelling with Description Logics

no code implementations25 Sep 2012 Alessandro Artale, Roman Kontchakov, Vladislav Ryzhikov, Michael Zakharyaschev

We design temporal description logics suitable for reasoning about temporal conceptual data models and investigate their computational complexity.

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