Net Operations

Two kinds of net operations, addition and Cartesian production of P/T nets, are introduced. They are defined on the set of underlying net of P/T systems. The conditions for preserving structural proper- ties of Petri net after these operations are discussed. It is shown that the set of P/T nets forms an Abelian group for net addition operation and the inverse net of a P/T net in usual meaning of net theo- ry is exactly the inverse of this P/T net as an element of the P/T net group; and that the set of P/T n…