Technical Reports

A List by Author: Pavlína Vařeková


Partial Order Reduction for State/Event LTL

by Nikola Beneš, Luboš Brim, Ivana Černá, Jiří Sochor, Pavlína Vařeková, Barbora Zimmerová, July 2008, 21 pages.

FIMU-RS-2008-07. Available as Postscript, PDF.


Software systems assembled from a large number of autonomous components become an interesting target for formal verification due to the issue of correct interplay in component interaction. State/event LTL incorporates both states and events to express important properties of component-based software systems.

The main contribution of the paper is a partial order reduction technique for verification of state/event LTL properties. The core of the partial order reduction is a novel notion of stuttering equivalence which we call state/event stuttering equivalence. The positive attribute of the equivalence is that it can be resolved with existing methods for partial order reduction. State/event LTL properties are, in general, not preserved under state/event stuttering equivalence. To this end we define a new logic, called weak state/event LTL, which is invariant under the new equivalence.

Model Checking of Control-User Component-Based Parametrised Systems

by Pavlína Vařeková, Ivana Černá, A full version of the paper presented at conference CBSE 2008. July 2008, 27 pages.

FIMU-RS-2008-06. Available as Postscript, PDF.


Many real component-based systems, so called Control-User systems, are composed of a stable part (control component) and a number of dynamic components of the same type (user components). Models of these systems are parametrised by the number of user components and thus potentially infinite. Model checking techniques can be used to verify only specific instances of the systems. This paper presents an algorithmic technique for verification of safety interaction properties of Control-User systems. The core of our verification method is a computation of a cutoff. If the system is proved to be correct for every number of user components lower than the cutoff then it is correct for any number of users. We present an on-the-fly model checking algorithm which integrates computation of a cutoff with the verification itself. Symmetry reduction can be applied during the verification to tackle the state explosion of the model. Applying the algorithm we verify models of several previously published component-based systems.

Component-Interaction Automata Modelling Language

by Ivana Černá, Pavlína Vařeková, Barbora Zimmerová, October 2006, 25 pages.

FIMU-RS-2006-08. Available as Postscript, PDF.


The paper introduces a Component-interaction automata language, which was designed for modelling of component interactions in hierarchical component-based software systems. The language supports modelling of important interaction attributes of such systems, and hence provides a rich base for further application of formal methods. Component-interaction automata provide a flexible form of component composition which can respect architectural assembly of the system, communication mechanisms, and other specifics of component-based systems. This allows the language to capture interactions in many different kinds of componentbased systems (built on different component models for instance). This paper provides a detailed study of the language including discussion of its practical application and comparison with related work. We intend to use this language as a framework for verifying coordination errors, checking of reconfiguration correctness, and formal analysis of component interactions in component-based systems, which is our ongoing and future work.

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