cs.DBAug 5, 2026

A General Sufficient Condition for Rewriting Horn-ALCHI Atomic Queries into GQL

Authors: David CarralCalixte GrusonQuentin Manière

Organizations: LIRMM, Inria, University of Montpellier, CNRS, Montpellier, France · DI ENS, ENS, CNRS, PSL University & Inria, France

Abstract

The emergence of the ISO standard GQL introduces a powerful query language extending first-order logic with controlled recursion, raising the question of its applicability to evaluation of ontology-mediated queries (OMQs). We focus on OMQs consisting of atomic queries over ontologies expressed in Horn-ALCHI, an expressive Description Logic that is not, in general, first-order rewritable. To address this, we introduce DL automata, a novel formalism that captures the semantics of such OMQs via runs over fact sets. We then identify a large class of DL automata that can be rewritten into unions of conjunctive two-way regular path queries (UC2RPQs), a central fragment of GQL. Our class of automata relies on a stratification of their states, ruling out specific forms of cyclic dependencies known to raise the complexity. This yields a broad class of Horn-ALCHI OMQs that are GQL-rewritable.

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