Reachable marking

Reachable marking --- достижимая разметка.

Let [math]\displaystyle{ N }[/math] be a Petri net. A marking [math]\displaystyle{ m }[/math] is called reachable for [math]\displaystyle{ N }[/math] iff there is a finite sequences of firings of the transitions of [math]\displaystyle{ N }[/math] leading [math]\displaystyle{ N }[/math] from the initial marking to [math]\displaystyle{ m }[/math]. All reachable markings of a Petri net [math]\displaystyle{ N }[/math] are denoted by [math]\displaystyle{ R(N). }[/math]