Abstract Model Repair

Model Repair George Chatzieleftheriou, Borzoo Bonakdarpour, Scott A. Smolka, and Panagiotis Katsaros 1 Department of Informatics, Aristotle University of Thessaloniki 54124 Thessaloniki, Greece 2 School of Computer Science, University of Waterloo 200 University Avenue West Waterloo N2L3G1, Canada 3 Department of Computer Science, Stony Brook University Stony Brook, NY 11794-4400, USA Abstract. Given a Kripke structure M and CTL formula φ, where M 6|= φ, the problem of Model Repair is to obtain a new model M ′ such that M ′ |= φ. Moreover, the changes made to M to derive M ′ should be minimal with respect to all such M ′. As in model checking, state explosion can make it virtually impossible to carry out model repair on models with infinite or even large state spaces. In this paper, we present a framework for model repair that uses abstraction refinement to tackle state explosion. Our model-repair framework is based on Kripke Structures, a 3-valued semantics for CTL, and Kripke Modal Transition Systems (KMTSs), and features an abstract-model-repair algorithm for KMTSs. Application to an Automatic Door Opener system is used to illustrate the practical utility of abstract model repair. Given a Kripke structure M and CTL formula φ, where M 6|= φ, the problem of Model Repair is to obtain a new model M ′ such that M ′ |= φ. Moreover, the changes made to M to derive M ′ should be minimal with respect to all such M ′. As in model checking, state explosion can make it virtually impossible to carry out model repair on models with infinite or even large state spaces. In this paper, we present a framework for model repair that uses abstraction refinement to tackle state explosion. Our model-repair framework is based on Kripke Structures, a 3-valued semantics for CTL, and Kripke Modal Transition Systems (KMTSs), and features an abstract-model-repair algorithm for KMTSs. Application to an Automatic Door Opener system is used to illustrate the practical utility of abstract model repair.