Graph Transformation Group
Welcome to the Graph Transformation Group (formerly Theoretical Computer Science) in the Department of Mathematics and Computer Science at the University of Bremen, Germany. The group belongs to the Technologie-Zentrum Informatik und Informationstechnik TZI [Centre for Computing and Communication Technologies] and of the interdisciplinary Bremen Research Cluster for Dynamics in Logistics LogDynamics.
Our research concentrates on graph transformation and other rule-based formalisms. Besides the mathematical foundation of the considered approaches, we investigate the relations to application areas including logistics, DNA computing, reversible circuits. Moreover, a smaller part of our work is devoted to various topics of Computer and Society.
Prof. Dr Hans-Jörg Kreowski, email@example.com
full professor (emeritus)
Dr Berthold Hoffmann, firstname.lastname@example.org
senior lecturer (retired)
Dr Sabine Kuske, email@example.com
lecturer and research assistant
Wolfgang Krieger firstname.lastname@example.org
Aaron Lye, email@example.com
Ph.D. student, scholarship with the Rosa-Luxemburg-Stiftung
Aljoscha Windhorst firstname.lastname@example.org
RESEARCHResearch of the Graph Transformation group concentrates on graph transformation and other rule-based formalisms. Besides the mathematical foundation of the considered approaches, we investigate the relations to application areas including logistics, DNA computing, reversible circuits. Moreover, a smaller part of our work is devoted to various topics of Computer and Society.
Graph transformationIn computer science it is often necessary to handle and to modify complex data representing, for instance, the structure of a software system or the behaviour of a process. In many cases these data can be suitably modelled as graphs. This general fact results in a great need for graph manipulating mechanisms that are powerful and comprehensible at the same time. In the theory of graph transformation such mechanisms are developed and investigated. The work of the group aims at a systematic extension of the theory and its application to different fields of practice. In particular, studies in the following areas are carried out:
Syntactic methods of picture generationThe study of syntactic methods of picture generation aims at using concepts and results from formal language and automata theory for picture generation. Besides the investigation of classical approaches like chain-code picture languages, L-systems with turtle geometry, cellular automata, array grammars, etc., especially collage grammars are studied. Typical subjects are:
These purely theoretical studies are accompanied by the development of systems that allow the evaluation and visualisation of collage grammars. The latest system in this line is COLLAGE-VR, which allows to define multi-coloured context-sensitive collage grammars in two as well as in three dimensions. The derived collages can be saved as PostScript files for inclusion in TeX documents, and they can be displayed. Three-dimensional collages are displayed using a standard VRML viewer. Moreover, the TREEBAG system provides a tree-based environment for picture generation using chain-code, collage, and turtle algebras.
If your browser has the shockwave flash plugin installed you may have a look at the following animations:here!
Or you may have a look at the short but illustrative generated movie by Caroline Diana von Totth (3D Show/8.5 MB/low resolution version).
Algebraic specificationFor all stages of software development, beginning with the requirements definition and ending with a running program, specification techniques are defined formally with respect to both syntax and semantics. The major emphasis is laid on:
The most important subjects are:
Research in this area contributes partly to CoFI (Common Framework Initiative for Algebraic Specification) within the IFIP Working Group 1.3. The goal of CoFI is to get a common agreement in the algebraic specification community about basic concepts, and to provide a family of specification languages at different levels, a development methodology, and tool support.
Computer and society
ProjectsThe working group was involved in the following projects funded by third parties: