Leszek Holenderski

Stess@Work: from measuring stress to its understanding, prediction and handling with personalized coaching

The problem of job stress is generally recognized as one of the major factors leading to a spectrum of health problems. People with certain professions, like intensive care specialists or call-center operators, and people in certain phases of their lives, like working parents with young children, are at increased risk of getting overstressed. For instance, one third of the intensive care specialists in the Netherlands are reported to have (had) a burn-out. Stress management should start far before the stress starts causing illnesses. The current state of sensor technology allows to develop systems measuring physical symptoms reflecting the stress level. We propose to use data mining and predictive modeling for gaining insight in the stress effects of the events at work and for enabling better stress management by providing timely and personalized coaching. In this paper we present a general framework allowing to achieve this goal and discuss the lessons learnt from the conducted case study.

The Synchronous Approach to Designing Reactive Systems

Synchronous programming is available through several formally defined languages having very different characteristics: Esterel is imperative, while Lustre and Signal are declarative in style; Statecharts and Argos are graphical languages that allow one to program by constructing hierarchical automata. Our motivation for taking the synchronous design paradigm further, integrating imperative, declarative (or dataflow), and graphical programming styles, is that real systems typically have components that match each of these profiles. This paper motivates our interest in the mixed language programming of embedded software around a number of examples, and sketches the semantical foundation of the Synchronie toolset which ensures a coherent computational model. This toolset supports a design trajectory that incorporates rapid prototyping and systematic testing for early design validation, an object oriented development methodology for long term software management, and formal verification at the level of automatically generated object code.

Model Checking SDL with Spin

We present an attempt to use the model checker Spin as a verification engine for SDL, with special emphasis put on the verification of timing properties of SDL models. We have extended Spin with a front-end that allows to translate SDL to Promela (the input language of Spin), and a back-end that allows to analyse timing properties. Compared with the previous attempts, our approach allows to verify not only qualitative but also quantitative aspects of SDL timers, and our translation of SDL to Promela handles the SDL timers in a correct way. We applied the toolset to the verification of a substantial part of a complex industrial protocol. This allowed to expose several non-trivial errors in the protocols design.

A Heuristic for Symmetry Reductions with Scalarsets

We present four versions of a new heuristic for coping with the problem of finding (canonical) representatives of symmetry equivalence classes (the so-called orbit problem), in symmetry techniques for model checking. The practical implementation of such techniques hinges on appropriate workarounds of this hard problem, which is equivalent to graph isomorphism. We implemented the four strategies on top of the Spin model checker, and compared their performance on several examples, with encouraging results.

A model checking project at Philips research

A new verification project has recently started at Philips Research. It concerns verification of C-like concurrent programs used to specify functionality of hardware-software systems. The problem is to make the verification practical, in the sense that it must be mechanized, and applicable to thousands of lines of C-like code. We present the goals of the project and some combination of existing solutions we want to try.