Polygonal hybrid systems (SPDI) are a subclass of planar hybrid
automata which can be represented by piecewise constant differential
inclusions. The reachability problem as well as the computation of certain objects of the phase portrait, namely the viability, controllability
and invariance kernels, for such systems is decidable. In this paper
we show how to compute another object of an SPDI phase portrait,
namely semi-separatrix curves and show how the phase portrait can
be used for reducing the state-space for optimizing the reachability
analysis.peer-reviewe
