Describing and verifying systems: a compositional algebra for Petri nets

A method for composing Petri nets is described. This is an application of a general categorical composition algebra. The example of a three-wire handshake is used to illustrate some features of this Petri net composition. The Petri net system provides knowledge of the underlying algebra which is invaluable in implementing strategies such as modular and hierarchic design. Having a high-level mathematical underpinning to a CAD system facilitates not only top-down design but also bottom-up verification.<>