Abstract: Control flow graphs are a well-known representation of
the sequential control flow structure of programs with a multitude
of applications. Not only single functions but also sets of functions
or complete programs can be modeled by control flow graphs. In
this case the size of the graphs can grow considerably and thus
makes it difficult for software engineers to analyze the control flow.
Graph reductions are helpful in this situation. In this paper we define
reductions to subsets of nodes. Since executions of programs are
represented by paths through the control flow graphs, paths should
be preserved. Furthermore, the composition of reductions makes a
stepwise analysis approach possible.