Kodkod: A Relational Model Finder

Abstract. We present an integration of the constraint solving kernel of the ProB model checker with the SMT solver Z3. We apply the combined solver to B and Event-B predicates, featuring higher-order datatypes and constructs like set comprehensions. To do so we rely on the finite set logic of Z3 and provide a new translation from B to Z3, better suited for constraint solving. Predicates can then be solved by the two solvers working hand in hand: constraints are set up in both solvers simultaneously and (intermediate) results are transferred. We thus combine a constraint logic programming based solver with a DPLL(T) based solver into a single procedure. The improved constraint solver finds application in many validation tasks, from animation of implicit specifications, to test case generation, bounded and symbolic model checking on to disproving of proof obligations. We conclude with an empirical evaluation of our approach focusing on two dimensions: comparing low and high-level encodings of B as well as comparing pure ProB to ProB combined with Z3.

Section: Related Workmentioning

confidence: 99%

SMT Solvers for Validation of B and Event-B Models

Krings

Leuschel

2016

“…The Alloy Analyzer [17] is used in the proof of the concept experiments. In the future, the Kodkod constraint solver [28] can be directly used for discharging symbolic constraints.…”

Section: Given a Privacy Policy Which Specifies The Purpose Retentiomentioning

confidence: 99%

“…We rely on the Alloy Analyzer [17] for model checking if a PV model satisfies a privacy policy specified in CTL-FO logic. Using SATbased model finder Kodkod [28], Alloy performs scope-restricted model finding. The Alloy specification supports first order relational logic [18], which is very convenient for specifying the transition system of a PV model.…”

Section: Overviewmentioning

confidence: 99%

“…The experiment shows that the verification cost explodes quickly with the number of states. More efficient verification can be performed, e.g., by invoking the Kodkod model finder [28] directly. An alternative is to prove privacy preservation by studying refinement relation between transition systems [2].…”

Section: Static Analysis For Constructing Transition Systemmentioning

confidence: 99%

See 1 more Smart Citation

Conformance Verification of Privacy Policies

2011

Abstract. Web applications are both the consumers and providers of information. To increase customer confidence, many websites choose to publish their privacy protection policies. However, policy conformance is often neglected. We propose a logic based framework for formally specifying and reasoning about the implementation of privacy protection by a web application. A first order extension of computational tree logic is used to specify a policy. A verification paradigm, built upon a static control/data flow analysis, is presented to verify if a policy is satisfied.

“…This approach requires the connection of UML and OCL with Boolean logic resulting in a bidirectional transformation. However, we make use of an intermediate language, relational logic, which is automatically and efficiently handled by the sophisticated model instance finder Kodkod [28]. Kodkod transforms relational models into SAT formulas and translates solutions fulfilling the SAT formulas back into relational instances.…”

Section: Introductionmentioning

confidence: 99%

From UML and OCL to Relational Logic and Back

Kuhlmann

Gogolla

2012

Abstract. Languages like UML and OCL are used to precisely model systems. Complex UML and OCL models therefore represent a crucial part of model-driven development, as they formally specify the main system properties. Consequently, creating complete and correct models is a critical concern. For this purpose, we provide a lightweight model validation method based on efficient SAT solving techniques. In this paper, we present a transformation from UML class diagram and OCL concepts into relational logic. Relational logic in turn represents the source for advanced SAT-based model instance finders like Kodkod. This paper focuses on a natural transformation approach which aims to exploit the features of relational logic as directly as possible through straitening the handling of main UML and OCL features. This approach allows us to explicitly benefit from the efficient handling of relational logic in Kodkod and to interpret found results backwards in terms of UML and OCL.