A Petri Net consists of a set of places, a set of transitions and a set of edges connecting places to transitions and transitions to places. It can be seen as a condition/event graph, where places are conditions and transitions are events. An event can occur if all conditions for the event hold. Places are usually represented as small circles while transitions are represented as thick lines. Usually, an edge enters a symbol from bottom to top.

Speaking in terms of graph properties, Petri Nets are directed graphs.

We suggest to represent Petri nets with upward drawings, i.e., drawings in which the edges tend to flow, as much as possible, in a common direction. Also, for Petri nets we suggest to represent edges with smoothed lines.

The following figure shows an example of a Petri net constructed with GDT.

GAPI tutorial on upward drawings and BLAG tutorial on upward drawings provide a comprehensive guide on how to use GDT to construct these widely used drawings.


Last update : July 31, 2002
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