Petri nets are a well-known model for parallel systems, used for both
applications and theoretical studies. They can be used for
specification, modelling, and analysis, and offer a graphical
representation and a clear view of concurrency. For the design of large
systems, modular construction is indispensible, and considerable effort
has been spent on studying themodular construction of Petri nets. This
book studies the modular construction of nets, and in particular the
top-down design of nets by action refinement. Suitable behavior
descriptions are presented and special care is taken to justify these
descriptions by showing that theyare necessary under reasonable
specification requirements. In particular, itis shown that partial-order
semantics is necessary to support action refinement.