I modeled Chris Crawford's conversation (Chris Crawford conversation model crawford conversation model) model in Petri Nets (Understanding Petri Nets for System Design). Drawn, it looks like this.

Basically, the token starts in the Idle State (p12), which is representative of the conversation not yet started.

From there, the token moves to either the left (t9) or the right (t8), signifying that the conversation has started. If t9 is fired first, Person 1 is listening (L1) and the Person 2 is speaking (S2).

After Person 2 speaks for a while, t11 fires, and Person 1 begins to think (T1) about what was said while Person 2 is now listening (L2) for a response. After an arbitrary time, Person 1 can transition (t7) to speaking (S1). We are now at a mirror reflection of the first marking.

The process repeats as many times as needed. There is currently no exit state - they must converse forever!

This is the most simplified net I could think to model as of Sept. 10, 2019.

#petrinet #toolong