Petri net (suomeksi)

Määritelmät:

One of several mathematical representations of discrete distributed systems, a 5-tuple $(S,T,F,M_0,W)\!$ , where
$S$ is a set of ''places''.
$T$ is a set of ''transitions''.
$S$ and $T$ are disjoint, i.e. no object can be both a place and a transition
$F$ is a set of arcs known as a ''flow relation''. The set $F$ is subject to the constraint that no arc may connect two places or two transitions, or more formally: $F \subseteq (S \times T) \cup (T \times S)$ .
$M_0 : S \to \mathbb{N}$ is an ''initial marking'', where for each place $s \in S$ , there are $n_s \in \mathbb{N}$ tokens.
$W : F \to \mathbb{N^+}$ is a set of ''arc weights'', which assigns to each arc $f \in F$ some $n \in \mathbb{N^+}$ denoting how many tokens are consumed from a place by a transition, or alternatively, how many tokens are produced by a transition and put into each place.