Publications

In this paper, we report on our research to improve the creation, implementation, and evolution of interoperability standards. Our approach was to systematically investigate a particular evolving interoperability standard, i.e., Teletext, to obtain relevant and beneficial insights that might generalize to other standards.

Many technical products and systems nowadays have functionality that is largely determined by software, so called software-intensive systems. The requirements for software-intensive systems change over time, causing the system to evolve. We define evolvability as the ability of the system to respond to such changes.

Although agent technology fits naturally to the control of the massively parallel processes in warehouses, agent-based warehouse management and control systems (WMCSs) have hardly been used in industry. We argue that model-driven development of such systems is crucial for their industrial applicability.

To increase the confidence in the correctness of software components, we investigated the use of two complementary formal methods in industrial software development. We combine a commercial refinement checker, the ASD:Suite of the company Verum, with the academic verification tool Uppaal to encompass a larger range of verification possibilities.

Probabilistic model checking has been used recently to assess, among others, dependability measures for a variety of systems. However, the numerical methods employed, such as those supported by model checking tools such as PRISM and MRMC, suffer from the state-space explosion problem. The main alternative is statistical model checking, which uses standard Monte Carlo simulation, but this performs poorly when small probabilities need to be estimated.

Multirate digital signal processing (DSP) algorithms are often modeled with synchronous dataflow graphs (SDFGs). A lower iteration period implies a faster execution of a DSP algorithm. Retiming is a simple but efficient graph transformation technique for performance optimization, which can decrease the iteration period without affecting functionality.

The two-player mean-payoff game is a well-known game theoretic model that is widely used, for instance in economics and control theory. For controller synthesis, a controller is modeled as a player while the environment, or plant, is modeled as the opponent player (adversary). Synthesizing an optimal controller that satisfies a given criterion corresponds to finding a winning strategy for the controller player.

Cyber-physical systems interact with their physical environment. In this interaction, non-functional aspects, most notably timing, are essential to correct operation. In modern systems, dynamism is introduced in many different ways. The additional complexity threatens timely development and reliable operation.