Networks describe the structure of systems, i.e. they capture the topology spanned by the components and their interactions. Accordingly, techniques of network theory aim at identifying and characterizing essential properties of a system from its structural representation. For example, the structure of a given reaction network may exclude bistable behavior irrespective of the parameters used. Network-theoretical methods are ubiquitously employed at the MPI for modeling and optimization of complex processes in physico-chemical/bio-chemical engineering and systems biology as well as for IC and MEMS design.

One important concept from network theory is modularization where process models are subdivided into elementary modeling units. These modules, once they are sufficiently characterized and parametrized, can conveniently be combined (and re-used) when setting up complex models. Modular modeling is an integral part of software tools developed at the MPI (ProMoT and Diana) facilitating the convenient setup and simulation of different systems such as membrane reactors, fuel cells or cellular signaling networks.

Methods of network theory play also a particular role in Systems Biology where biological systems can often only be analyzed from their underlying network structure because quantitative details are usually unknown. CellNetAnalyzer is a software package developed at the MPI providing various algorithms for analyzing structure and function of biochemical reaction networks. The methods and tools developed in the field of network theory provide a common infrastructure for systems and process engineering actively used by several MPI groups as well as by the international scientific community.