Deciding MSO over Languages of Hypergraphs

The description of sets of words (called languages) is a well known fieldof research. However a less popular extension of this concept is formed by languages of relational structures like hypergraphs. For hypergraphs one possibility is given by hyperedge replacement grammars. In analogy to context free string grammars they form a system of nonterminal hyperedges(symbols), hypergraphs(words) and production rules that specify

how nonterminal hyperedges can be replace in order to derive different hypergraphs. As for strings we can describe properties of hypergraphs by first oder logic (FO) and monadic second order logic (MSO). Both include quantification over vertices and predication about hyperedges. MSO extends FO by the quantification over subsets of vertices. Deciding properties for a single hypergraph is mostly trivial while checking properties for languages of structures is not decidable in general. However the decidability of MSO-formulas over hypergraphs was proven by B. Courcelle for languages described by hyperedge replacement grammars, but no applicable algorithm to decide this problem was given.

I present the results of my thesis where I develop an algorithm to decide if a property given as a MSO formula is fulfilled by a set of hypergraphs defined by a hyperedge replacement grammar and thereby provide a different, constructive proof of the decidability.

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.