Further Examination For Iterative Siphon Control In Petri Nets

This thesis focuses on deadlock prevention in Petri nets. Three algorithms of siphon iterative control are first analysized and examined. The three algorithms, based on covering set of uncontolled minimal siphons, combine markings with minimal siphons. The states of a Petri net are considerated as well, which makes a Petri net, by means in the algorithms, can be ususally controlled optimally. After the three algorithms, a new one is proposed, in which a method for control of an ordinary Petri net is used for a generalized one, via transformation from a generalized Petri net to an ordinary one and back-transformation from a controlled one to an ordinary net. In the algorithms above, many promblems are involved, such as minimal siphon enumeration, transformation from a generalized Petri net to an ordinary one and back-transformation from a controlled one to a generalized, covering set of uncontrolled minimal siphons, generation of critical markings, deadlock generation problem, removing redundant control places, etc. And to solve the problems, integer linear programming is useful.