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

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.

27 pages. Technical report of a paper to appear at ISWC 2026

Databases (cs.DB); Artificial Intelligence (cs.AI)

arXiv:2608.04945 [cs.DB]

(or arXiv:2608.04945v1 [cs.DB] for this version)

https://doi.org/10.48550/arXiv.2608.04945 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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