Two Petri Nets Models to approach the Dining Philosophers Problem

The Dining Philosophers Problem is a classic example of describing Concurrency operation in operating system, and generally such methods as Monitor, PV operation, etc, are used to avoid the deadlock problem. With the Petri nets as a good tool of describing and analyzing concurrent problem, the paper proposes one Petri nets model to avoid deadlock, and further discusses the method of using another expend Petri nets model to prevent the infinite waiting situation occurring.