First-Order Rewritability of Frontier-Guarded Ontology-Mediated Queries

11/18/2020
by   Pablo Barceló, et al.
0

We focus on ontology-mediated queries (OMQs) based on (frontier-)guarded existential rules and (unions of) conjunctive queries, and we investigate the problem of FO-rewritability, i.e., whether an OMQ can be rewritten as a first-order query. We adopt two different approaches. The first approach employs standard two-way alternating parity tree automata. Although it does not lead to a tight complexity bound, it provides a transparent solution based on widely known tools. The second approach relies on a sophisticated automata model, known as cost automata. This allows us to show that our problem is 2ExpTime-complete. In both approaches, we provide semantic characterizations of FO-rewritability that are of independent interest.

READ FULL TEXT

page 1

page 2

page 3

page 4

research
10/22/2020

From Conjunctive Queries to Instance Queries in Ontology-Mediated Querying

We consider ontology-mediated queries (OMQs) based on expressive descrip...
research
04/29/2019

A Complete Classification of the Complexity and Rewritability of Ontology-Mediated Queries based on the Description Logic EL

We provide an ultimately fine-grained analysis of the data complexity an...
research
06/13/2023

Temporalising Unique Characterisability and Learnability of Ontology-Mediated Queries

Recently, the study of the unique characterisability and learnability of...
research
08/14/2018

Evaluating Datalog via Tree Automata and Cycluits

We investigate parameterizations of both database instances and queries ...
research
01/31/2019

Query Inseparability for ALC Ontologies

We investigate the problem whether two ALC ontologies are indistinguisha...
research
10/14/2019

Dynamic Complexity of Parity Exists Queries

Given a graph whose nodes may be coloured red, the parity of the number ...
research
10/15/2020

Reducing (to) the Ranks: Efficient Rank-based Büchi Automata Complementation (Technical Report)

This paper provides several optimizations of the rank-based approach for...

Please sign up or login with your details

Forgot password? Click here to reset