Passed the test of time: Saarbrücken computer scientist honoured for influential research work

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Computer science professor Holger Hermanns has received international honors for his work. Photo: Oliver Dietze

Computer science professor Holger Hermanns and colleagues have been awarded the “Jean-Claude Laprie Award in Dependable Comptung” for a research paper in which they developed a new method for checking models. The prize is awarded annually since 2012 and acknowledges outstanding work that has significantly shaped the theory and practice of the research field “Dependable Computing”. The award ceremony will take place on 29 June in Porto, Portugal, at the 53rd “International Conference on Dependable Systems and Networks”.

Working on and with models, as in representations of certain facts in the real world, is the bread and butter of numerous sciences. Whether, for example, meteorological models used for weather forecasting, biological models such as the double helix DNA, or epidemiological models used to describe the outbreak during the Corona pandemic – they enable researchers to look at certain aspects of the world in isolation and under controlled conditions.

Models also play a central role in computer science. For example, there are models to calculate whether an algorithm can be executed in time under certain conditions. Or models that can be used to prove that an algorithm is the fastest for a particular use case. “Modelling like this can contribute to safer and more reliable software, because with its help important questions about the properties of an algorithm can be clarified before it is implemented in a final product,” explains Saarbrücken computer science professor Holger Hermanns.

Models are themselves a field of research in their own right. “First of all, one has to know how to get an adequate model of a system in the first place. Then one has to know: What and, above all, how can I ‘interrogate’ my model properly in order to gain insights from it?” says Hermanns. The latter aspect is the subject of the paper “Model-checking algorithms for continuous-time Markov chains” published in 2003 in the “IEEE Transactions of Software Engineering”, for which he and his colleagues Christel Baier, Boudewijn Haverkort, and Joost-Pieter Katoen have now been honored by the “Working Group on Dependable Computing and Fault Tolerance” of the “International Federation for Information Processing (IFIP)”. The paper has profoundly influenced research and practice on the design and evaluation of dependable and safety-critical systems.

“We have looked at so-called Markov chains. These are mathematical models that can indicate how high the probability is that a system is in a certain state over a certain period of time – or at a certain point in time. For example: ‘What is the probability that the nuclear fuel supply of a power plant is still below the critical temperature limit at 5 p.m.'”, explains Holger Hermanns. Markov chains are accordingly often used in the research field of performance evaluation. “Until our work, performance evaluation had a rather limited ‘catalogue of questions’ and could thus only read comparatively surface information from its models,” explains Holger Hermanns. “We have adapted complex logics from theoretical computer science for performance evaluation applications and thus developed a new ‘language’ that can be used to probe a model with complex, nested queries,” explains the Saarbrücken computer science professor. These more detailed “questioning options” help to better assess the modelled systems and thus ensure correct functioning.

The paper by Hermanns and colleagues is one of the 100 most cited papers in the “IEEE Transactions on Software Engineering” and has influenced numerous model checking procedures. Systems based on the researchers’ approach are used, for example, in safety-critical infrastructures such as nuclear power plants, and the European Space Agency ESA and the car manufacturer BMW also use the approach to assess the reliability of their systems.

In 2022, Christel Baier, Holger Hermanns and Joost-Pieter Katoen received the “Test of Time Award” from the International Conference on Concurrency Theory (CONCUR) for a closely related work. “To receive awards at two internationally renowned conferences within such a short period of time is a great pleasure and confirms that we were on the trail of something important almost 20 years ago,” says Holger Hermanns.


Further Information
About the Jean-Claude Laprie Award:
About the CONCUR Test of Time Award:


Background Saarland Informatics Campus:
900 scientists (including 400 PhD students) and about 2500 students from more than 80 nations make the Saarland Informatics Campus (SIC) one of the leading locations for computer science in Germany and Europe. Four world-renowned research institutes, namely the German Research Center for Artificial Intelligence (DFKI), the Max Planck Institute for Informatics, the Max Planck Institute for Software Systems, the Center for Bioinformatics as well as Saarland University with three departments and 24 degree programs cover the entire spectrum of computer science.

Philipp Zapf-Schramm
Saarland Informatics Campus
Phone: +49 681 302-70741


Philipp Zapf-Schramm
Saarland Informatics Campus
Telefon: +49 681 302-70741