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Efficient OWL2QL Meta-reasoning Using ASP-based Hybrid Knowledge Bases

Haya Majid Qureshi, Wolfgang Faber

TL;DR

Improve the theoretical basis of the reductions and by using alternative tools that show competitive performance are improved by improving the theoretical basis of the reductions and by using alternative tools that show competitive performance.

Abstract

Metamodeling refers to scenarios in ontologies in which classes and roles can be members of classes or occur in roles. This is a desirable modelling feature in several applications, but allowing it without restrictions is problematic for several reasons, mainly because it causes undecidability. Therefore, practical languages either forbid metamodeling explicitly or treat occurrences of classes as instances to be semantically different from other occurrences, thereby not allowing metamodeling semantically. Several extensions have been proposed to provide metamodeling to some extent. Building on earlier work that reduces metamodeling query answering to Datalog query answering, recently reductions to query answering over hybrid knowledge bases were proposed with the aim of using the Datalog transformation only where necessary. Preliminary work showed that the approach works, but the hoped-for performance improvements were not observed yet. In this work we expand on this body of work by improving the theoretical basis of the reductions and by using alternative tools that show competitive performance.

Efficient OWL2QL Meta-reasoning Using ASP-based Hybrid Knowledge Bases

TL;DR

Improve the theoretical basis of the reductions and by using alternative tools that show competitive performance are improved by improving the theoretical basis of the reductions and by using alternative tools that show competitive performance.

Abstract

Metamodeling refers to scenarios in ontologies in which classes and roles can be members of classes or occur in roles. This is a desirable modelling feature in several applications, but allowing it without restrictions is problematic for several reasons, mainly because it causes undecidability. Therefore, practical languages either forbid metamodeling explicitly or treat occurrences of classes as instances to be semantically different from other occurrences, thereby not allowing metamodeling semantically. Several extensions have been proposed to provide metamodeling to some extent. Building on earlier work that reduces metamodeling query answering to Datalog query answering, recently reductions to query answering over hybrid knowledge bases were proposed with the aim of using the Datalog transformation only where necessary. Preliminary work showed that the approach works, but the hoped-for performance improvements were not observed yet. In this work we expand on this body of work by improving the theoretical basis of the reductions and by using alternative tools that show competitive performance.

Paper Structure

This paper contains 13 sections, 3 theorems, 1 equation, 7 figures, 1 table.

Key Result

Proposition 1

Let $\mathcal{O}$ be a consistent OWL 2 QL ontology and $\mathcal{Q}$ a conjunctive SPARQL query. Then, $ANS(\mathcal{Q},\mathcal{O}\xspace) = ANS(q,\mathcal{K}^{E\!-\!AT{}}_{All}(\mathcal{O}\xspace,\mathcal{Q}))$, where $q$ is the query predicate introduced by $\tau^{q}(\mathcal{Q})$.

Figures (7)

  • Figure 1: The Overall Architecture of Hybrid-Framework
  • Figure 2: LUBM(1) experiments with standard and meta queries
  • Figure 3: LUBM(9) experiments with Standard and Meta Queries
  • Figure 4: MODEUS(00) with Meta Queries
  • Figure 5: MODEUS(01) with Meta Queries
  • ...and 2 more figures

Theorems & Definitions (15)

  • Definition 1
  • Definition 2
  • Definition 3
  • Definition 4
  • Definition 5
  • Definition 6
  • Definition 7
  • Definition 8
  • Proposition 1
  • proof
  • ...and 5 more