The Petri network is a mathematical representation of the discrete parallel system. The Petri network was invented by C.A. Peti in the 1960s, suitable for describing asynchronous, concurrent computer system models. The Petri network has both strict mathematical expressions, as well as intuitive graphical expression.
Since Petri network can express the concurrency, it is considered to be one of the theory of automation. The research field trend believes that Petri.com is a mother of all process definition languages.
Classic Petri
The classic Petri network is a simple process model, composed of two nodes: library and changes, arcing arc, and token and other elements.
structure
PETRI network element:
Transition-circular node change (connection) is an arc as a library and the change in the reservoir, and token is a dynamic object in the library, which can move from a library. To another library.
The rules of the Petri network are:
An arc is a direction or change between two library or changes in the direction, any number of tokens.
behavior
If a changed place has a token, this change is enabled. When a change is allowed, the change will occur (fire), the token of the input library (INPUT Place) is consumed, and the token is generated for the output location.
note:
The occurrence of changes is atomic; there are two changes that are allowed, but only one change can occur at a time; if there is a change, its number of input library is not equal to the number of output library, token The number will change; the Petri network is static; the status of the Petri network is determined by the token distribution in the library.
Two changes to a token is called conflict
A plurality of arcs connect two nodes. The number of arcs between the input library and the changes determine the number of tokens that the change is changed to be allowed. The number of arcs determines the number of tokens that consume / generate. Can refer to BLOG of Silver Fox 999
