Thomas Ströder

Towards Termination Analysis of Real Prolog Programs

When developing programs it is of great practical interest to verify that the
resulting programs have the desired properties. One of the most fundamental
properties of programs is termination, i.e., that the program will not run
forever, but compute some result in finitely many computation steps. The
corresponding decision problem in computer science is the halting problem, i.e.,
given a description of a program and an input, decide whether the program
terminates after finitely many steps or runs forever on that input.
Unfortunately, Turing showed this problem to be undecidable in general.
Nevertheless, a huge number of analysis techniques which can automatically prove
termination for many pairs of programs and inputs have been developed during the
last decades. Nowadays, there are fully-automated tools that try to prove
termination of a given program w.r.t. a given class of inputs.
However, most approaches for proving termination of programs are restricted to
artificial programming languages having a comparatively simple mathematical
definition and cannot handle essential features of programming languages used
for real applications where exact mathematical definitions are very complex.
This is especially true for logic programming, where most techniques for
termination analysis are restricted to definite logic programs in contrast to
real applications mostly written in the programming language Prolog, the main
language for expert systems and applications from the artificial intelligence
domain.
In this thesis, we extend the only existing approach known to be capable of
handling logic programs with cuts to cover most of the features of real Prolog
applications.
The contributions developed in this thesisare implemented in our fully automated
termination prover AProVE.AProVE has reached the highest score for logic
programming at the annual international Termination Competition, where the
leading automated tools try to analyze termination of programs from different
areas of computer science, in all years since 2004. In 2009, AProVE also was the
only tool capable of successfully analyzing logic programs with cuts. The
significance of our results is demonstrated by the empirical improvementAProVE
shows on real Prolog applications used in the Termination Competition.

BSc/MSc/Diploma Topics
Teaching WS 2012/13
Hybrid Systems Group

We are looking for a HiWi for the Compiler Construction course. If you are interested, please contact Thomas Noll.

Joost-Pieter Katoen has been appointed as a member of the renowned Academia Europaea (Academy of Europe), a European, non-governmental association acting as an Academy whose members are scientists and scholars who collectively aim to promote learning, education and research.

Vacancies for postdoctoral researchers in "Automated Analysis of Probabilistic Programs". Application deadline: August 15, 2013.

Joost-Pieter Katoen has been awarded a Distinguished Professorship from the RWTH Aachen University.

The Hybrid Systems: Computation and Control (HSCC'13) conference in Philadelphia has been very successful: Hongfei Fu received the best student paper award for his paper "Approximating acceptance probabilities of CTMC-paths on multi-clock deterministic timed automata". Besides, the paper by Ilya Tkachev, Alexandru Mereacre, Alessandro Abate and Joost-Pieter Katoen was ranked second in the overall best paper award selection.

Joost-Pieter Katoen has been elected as Steering Committee Chair of ETAPS (www.etaps.org), the largest conference on theory and practice of software in Europe. He is the first non-UK ETAPS SC chair since the conference was initiated in 1998. More information here.

The Alumni-Magazine of RWTH Aachen University contains an interview with our former PhD student and postdoctoral researcher, Dr. Tingting Han.

HiWi's wanted to work in a new European Space Agency project for enhancing state-of-the-art design and analysis tools (COMPASS) for the next generation European rockets. Need programming and model checking affinity. See here for details and contact.

We offer openings for several PhD candidates in the area of
"Model-Based Design and Analysis for Dependable Software Systems". Deadline for application: September 14, 2012. For further information click here.

The Theory of Hybrid Systems Group offers two jobs as student assistants within the CEBug project. For more information, look here.

Dino Distefano received the prestigious Roger Needham Award for his work on software verification. This award is for a distinguished research contribution in computer science by a UK based researcher who has completed up to 10 years of post-doctoral research. Dr. Distefano was the first PhD student supervised by Joost-Pieter Katoen.

Marijn Jongerden received the German MMB (Messung, Modellierung und Bewertung von Rechensystemen) Award 2012 of the GI/ITG-Committee for Measurement, Modelling and Evaluation of Computing Systems for his PhD-thesis on "Model-based energy analysis of battery powered systems". His work was supervised by Boudewijn Haverkort (Twente) and Joost-Pieter Katoen.

Our paper "Formal Correctness, Safety, Dependability and Performance Analysis of a Satellite" has been accepted to ICSE 2012 in the track SE in Practice (18% acceptance rate). The paper treats a new satellite from the European Space Agency that was modeled and analyzed with modern tools during the actual satellite design.

Joost-Pieter Katoen will act as DJ in the "Nacht der Professoren" in the Apollo bar and cinema.