Andrzej Zbrzezny

Towards Bounded Model Checking for the Universal Fragment of TCTL

Bounded Model Checking (BMC) based on SAT methods consists in searching for a counterexample of a particular length and to generate a propositional formula that is satisfiable iff such a counterexample exists. Our paper shows how the concept of bounded model checking can be extended to deal with TACTL (the universal fragment of TCTL) properties of Timed Automata.

A New Translation from ECTL* to SAT

In this paper we present a new translation from ECTL* to SAT and show that the proposed translation substantially increases the efficiency of verifying temporal properties using the Bounded Model Checking method. We have implemented our new translation and made experimental results, which demonstrate the efficiency of the method.

SAT-Based Bounded Model Checking for Weighted Interpreted Systems and Weighted Linear Temporal Logic

We present a SAT-based bounded model checking (BMC) method for the weighted interpreted systems (i.e. interpreted systems augmented to include a weight function, one per each agent, that associates weights with actions, which are arbitrary natural numbers) and for properties expressible in the existential fragment of a weighted linear temporal logic with epistemic components (WELTLK). Since in BMC we translate both the system model and the checked specification to a propositional formula that is later analysed by a SAT-solver, we report on a propositional encoding of both the weighted interpreted systems and the WELTLK formulae. This encoding is designed specifically for managing weighted temporal operators and knowledge operators, which are commonly found in properties of multi-agent systems in models of which we assume that acting of agents may cost. We implemented the proposed BMC algorithm as a new module of VerICS, and we evaluated it by means of the following two examples: a weighted generic pipeline paradigm and a weighted bits transmission problem.

The BMC method for the existential part of RTCTLK and interleaved interpreted systems

In the paper, we focus on the formal verification of multi-agent systems - modelled by interleaved interpreted systems - by means of the bounded model checking (BMC) method, where specifications are expressed in the existential fragment of the Real-Time Computation Tree Logic augmented to include standard epistemic operators (RTECTLK). In particular, we define an improved SAT-based BMC for RTECTLK, and present performance evaluation of our newly developed BMC method by means of the well known train controller and generic pipeline systems.

SAT-Based Verification of Security Protocols Via Translation to Networks of Automata

In this paper we show a novel method for modelling behaviours of security protocols using networks of communicating automata in order to verify them with SAT-based bounded model checking. These automata correspond to executions of the participants as well as to their knowledge about letters. Given a bounded number of sessions, we can verify both correctness or incorrectness of a security protocol proving either reachability or unreachability of an undesired state. We exemplify all our notions on the Needham Schroeder Public Key Authentication Protocol (NSPK) and show experimental results for checking authentication using the verification tool VerICS.

Towards SAT-based BMC for LTLK over Interleaved Interpreted Systems

This paper makes two contributions to the verification of multi-agent systems modelled by interleaved interpreted systems. Firstly, the paper presents theoretical underpinnings of the SAT-based bounded model checking (BMC) approach for LTL extended with the epistemic component (LTLK) over interleaved interpreted systems. Secondly, the BMC method has been implemented and tested on several benchmarks for MAS. The preliminary experimental results reveal advantages and disadvantages of our SAT-based BMC for LTLK and show that the method has a significant potential.

SAT-based (parametric) reachability for a class of distributed time Petri nets

Formal methods - among them the model checking techniques - play an important role in the design and production of both systems and software. In this paper we deal with an adaptation of the bounded model checking methods for timed systems, developed for timed automata, to the case of time Petri nets. We consider distributed time Petri nets and parametric reachability checking, but the approach can be easily adapted to verification of other kinds of properties for which the bounded model checking methods exist. A theoretical description is supported by some experimental results, generated using an extension of the model checker VerICS.

Checking ACTL* properties of discrete timed automata via bounded model checking

The main contribution of the paper consists in showing that the BMC method is feasible for ACTL * (the universal fragment of CTL * which subsumes both ACTL and LTL. The extension to ACTL * is obtained by redefining the function returning the sufficient number of executions over which an ACTL * formula is checked, and then by combining two known translations to SAT for ACTL and LTL formulas. The proposed translation of ACTL * formulas is essentially different from the existing translations of both ACTL and LTL formulas. Moreover, ACTL * seems to be the largest set of temporal properties which can be verified by means of BMC. We have implemented our new BMC algorithm for discrete timed automata and we have presented a preliminary experimental results, which prove the efficiency of the method. The formal treatment is the basis for the implementation of the technique in the symbolic model checker \(\surd\)erics.

SAT-Based BMC for Deontic Metric Temporal Logic and Deontic Interleaved Interpreted Systems

We consider multi-agent systems’ (MASs) modelled by deontic interleaved interpreted systems and we provide a new SAT-based bounded model checking (BMC) method for these systems. The properties of MASs are expressed by means of the metric temporal logic with discrete semantics and extended to include epistemic and deontic operators. The proposed BMC approach is based on the state of the art solutions to BMC. We test our results on a typical MASs scenario: train controller problem with faults.

A Translator of Java Programs to TADDs

The model checking tools Uppaal and VerICS accept a description of a network of Timed Automata with Discrete Data (TADDs) as input. Thus, to verify a concurrent programwritten in Java by means of these tools, first a TADD model of the program must be build. Therefore, we have developed the J2TADD tool that translates a Java program to a network of TADDs; the paper presents this tool. The J2TADD tool works in two stages. The first one consists in translation of a Java code to an internal assembly language (IAL). Then, the resulting assembly code is translated to a network of TADDs. We exemplify the use of the translator by means of the following well-known concurrency examples written in Java: race condition problem, dining philosophers problem, single sleeping barber problem and readers and writers problem.