Bożena Woźna

A complete and decidable security-specialised logic and its application to the TESLA protocol

We examine a logic to reason about security protocols by means of temporal and epistemic concepts. We report results on completeness and decidability of the formalism as well as its expressiveness. As a case study we apply the formalism in the analysis of TESLA, a secure stream multi-cast protocol.

A complete and decidable axiomatisation for deontic interpreted systems

We solve the problem left open in [5] by providing a complete axiomatisation of deontic interpreted systems on a language that includes full CTL as well as the Ki, Oi and

A logic for knowledge, correctness, and real time

{\mathcal{\widehat{\rm {K}}}}^j_i

A combination of explicit and deductive knowledge with branching time: completeness and decidability results

modalities. Additionally we show that the logic employed enjoys the finite model property, hence decidability is guaranteed. To achieve these results we follow and extend the technique used by Halpern and Emerson in [2].

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

We present TCTLKD, a logic for knowledge, correctness and real time. TCTLKD is interpreted on real time deontic interpreted systems, and extension to continuous time of deontic interpreted systems. We exemplify the use of TCTLKD by discussing a variant of the railroad crossing system.

A Translator of Java Programs to TADDs

Logics for knowledge and time comprise logic combinations between epistemic logic S5n for n agents and temporal logic. In this paper we examine a logic combination of Computational Tree Logic and an epistemic logic augmented to include an additional epistemic operator representing explicit knowledge. We show the resulting system enjoys the finite model property, decidability and is finitely axiomatisable. It is further shown that the expressivity of the resulting system enables us to represent a non-standard notion of deductive knowledge which seems promising for applications.

Bounded Model Checking Real-Time Multi-agent Systems with Clock Differences: Theory and Implementation

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.

Bounded Model Checking for the Universal Fragment of CTL

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.

VerICS 2007 - a Model Checker for Knowledge and Real-Time

We present a methodology for verifying epistemic and real-time temporal properties of multi-agent systems. We introduce an interpreted systems semantics based on diagonal timed automata and use a real-time temporal epistemic language to describe properties of multi-agent systems. We develop a bounded model checking algorithm for this setting and present experimental results for a real-time version of the alternating bit-transmission problem obtained by means of a preliminary implementation of the technique.