Controlled Query Evaluation (CQE) has been recently studied in the context of Semantic Web ontologies. The goal of CQE is concealing some query answers so as to prevent external users from inferring confidential information. In general, there exist multiple, mutually incomparable ways of concealing answers, and previous CQE approaches choose in advance which answers are visible and which are not. In this paper, instead, we study a dynamic CQE method, namely, we propose to alter the answer to the current query based on the evaluation of previous ones. We aim at a system that, besides being able to protect confidential data, is maximally cooperative, which intuitively means that it answers affirmatively to as many queries as possible; it achieves this goal by delaying answer modifications as much as possible. We also show that the behavior we get cannot be intensionally simulated through a static approach, independent of query history. Interestingly, for OWL 2 QL ontologies and policy expressed through denials, query evaluation under our semantics is first-order rewritable, and thus in AC⁰ in data complexity. This paves the way for the development of practical algorithms, which we also preliminarily discuss in the paper.

Controlled Query Evaluation in OWL 2 QL: A "Longest Honeymoon" Approach / Bonatti, Piero; Cima, Gianluca; Lembo, Domenico; Marconi, Lorenzo; Rosati, Riccardo; Sauro, Luigi; Savo, Domenico Fabio. - 13489 LNCS:(2022), pp. 428-444. (Intervento presentato al convegno International Semantic Web Conference tenutosi a Hangzhou; China) [10.1007/978-3-031-19433-7_25].

Controlled Query Evaluation in OWL 2 QL: A "Longest Honeymoon" Approach

Gianluca Cima;Domenico Lembo;Lorenzo Marconi
;
Riccardo Rosati;Domenico Fabio Savo
2022

Abstract

Controlled Query Evaluation (CQE) has been recently studied in the context of Semantic Web ontologies. The goal of CQE is concealing some query answers so as to prevent external users from inferring confidential information. In general, there exist multiple, mutually incomparable ways of concealing answers, and previous CQE approaches choose in advance which answers are visible and which are not. In this paper, instead, we study a dynamic CQE method, namely, we propose to alter the answer to the current query based on the evaluation of previous ones. We aim at a system that, besides being able to protect confidential data, is maximally cooperative, which intuitively means that it answers affirmatively to as many queries as possible; it achieves this goal by delaying answer modifications as much as possible. We also show that the behavior we get cannot be intensionally simulated through a static approach, independent of query history. Interestingly, for OWL 2 QL ontologies and policy expressed through denials, query evaluation under our semantics is first-order rewritable, and thus in AC⁰ in data complexity. This paves the way for the development of practical algorithms, which we also preliminarily discuss in the paper.
2022
International Semantic Web Conference
ontologies; data protection; description logics; first-order rewritability
04 Pubblicazione in atti di convegno::04b Atto di convegno in volume
Controlled Query Evaluation in OWL 2 QL: A "Longest Honeymoon" Approach / Bonatti, Piero; Cima, Gianluca; Lembo, Domenico; Marconi, Lorenzo; Rosati, Riccardo; Sauro, Luigi; Savo, Domenico Fabio. - 13489 LNCS:(2022), pp. 428-444. (Intervento presentato al convegno International Semantic Web Conference tenutosi a Hangzhou; China) [10.1007/978-3-031-19433-7_25].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1651064
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