无界公平Petri网的进程表达式

Process Expression of Unbounded Fair Petri Nets

Ｐｅｔｒｉ网的进程表达式是以该网系统的基本子进程集为字母表的一个正规表达式．它用有限形式给出了网系统的所有（无限多个）进程的集合．作者于１９９５年给出了对任意给定的有界Ｐｅｔｒｉ网求其进程表达式的一个算法．这个算法对无界Ｐｅｔｒｉ网是不适用的，其原因在于子进程同构的概念在无界网系统中没有意义．对此，作者通过定义进程段行为等价的概念，导出了无界Ｐｅｔｒｉ网的进程表达式的一般形式，并借助无界公平网的特征可达树得出求给定无界公平网进程表达式的一个算法。

Process expression of a Petri net is a regular expression with the basic subprocess set of the net system as alphabet. It defines the process set of the net system. Author presented an algorithm to fine the process expression for any given bounded Petri net in 1995. However, the algorithm is not suitable for unbounded Petri nets, because the concept of isomorphism between subprocesses is not valid for unbounded Petri nets. By means of the concept of behave equivalence between process sections, the normal form of process expressions of unbounded fair Petri nets is obtained and an algorithm to find the process expression of a given unbounded fair Petri net presume on the characteristic reachability tree of the net system is given in this paper.