CQE in Description Logics Through Instance Indistinguishability (extended version)

TL;DR

This paper investigates privacy-preserving query answering in Description Logics using controlled query evaluation based on instance indistinguishability, providing complexity results and a tractable, first-order rewritable approximation for DL-Lite ontologies.

Contribution

It introduces a new, semantically well-founded approximation for CQE in DLs that is tractable and first-order rewritable for DL-Lite$_{ ext{R}}$ ontologies.

Findings

Data complexity results for CQE in DL-Lite$_{ ext{R}}$

Comparison with existing confidentiality approaches

Proved tractability and first-order rewritability of the approximation

Abstract

We study privacy-preserving query answering in Description Logics (DLs). Specifically, we consider the approach of controlled query evaluation (CQE) based on the notion of instance indistinguishability. We derive data complexity results for query answering over DL-Lite$_{\mathcal{R}}$ ontologies, through a comparison with an alternative, existing confidentiality-preserving approach to CQE. Finally, we identify a semantically well-founded notion of approximated query answering for CQE, and prove that, for DL-Lite$_{\mathcal{R}}$ ontologies, this form of CQE is tractable with respect to data complexity and is first-order rewritable, i.e., it is always reducible to the evaluation of a first-order query over the data instance.