Petri nets are a popular graphical way of modeling concurrent systems such as
communications protocols, multiprocessor computers etc. With Petri nets it is
possible to assess the correctness of systems for example by verifying that
the system cannot deadlock, that there cannot be any buffer overflows etc.

PIPEs main aim is to improve on existing tools available for modeling Petri
Nets. A key design feature is the modular approach adopted for analysis,
enabling new modules to written easily and powerfully, using built-in data
layer methods for standard calculations. Six analysis modules have been
written (so far) including Invariant Analysis, State-Space Analysis (deadlock,
etc), Simulation Analysis & Classification. PIPE adheres to the latest XML
Petri net standard (PNML). File format for saving and loading Petri-Nets is
also extensible through the use of XSLT, the default being PNML.

WWW: http://petri-net.sourceforge.net/