# Reachability graph for Petri net.

I am trying to draw a reachability graph for this Petri net. Could you please help me to understand how this works?

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You know how Petri nets work? Homework? –  Hendrik Jan Jan 16 '13 at 21:34
actually not homework. I'm learning for my exams. –  alex Jan 16 '13 at 21:59
Where can we help? Is it the way Petri Nets work, or are you stuck with the reachability graph? –  Hendrik Jan Jan 16 '13 at 22:03
reachability graph only. –  alex Jan 16 '13 at 22:43

In your example start with a node representing the initial marking $(5,0,3,2,0)$. In this marking transition $T0$ taking $1$ from places $P0$ and $P2$ each, while adding $1$ to place $P1$. The resulting marking is $(4,1,2,2,0)$. Add an edge labelled by $T0$ from the first to second marking.
In the same initial marking also $T2$ is enabled, add an edge to the marking that results after firing. Continue this way, visiting the newly generated markings, until all possibilities are taken care of.