State The state of the system is modeled by marking the places with tokens a place can be marked with a finite number(possibly zero) of tokens
State ◼ The state of the system is modeled by marking the places with tokens ◼ A place can be marked with a finite number (possibly zero) of tokens
Ire a transition t is called enabled in a certain marking, if o For every arc from a place p to t, there exists a distinct token in the marking An enabled transition can fire and result in a new marking Firing of a transition t in a marking is an atomic operation state transition of form(1,0)>(0, 1) p1: input place p2: output place p2
Fire ◼ A transition t is called enabled in a certain marking, if: For every arc from a place p to t, there exists a distinct token in the marking ◼ An enabled transition can fire and result in a new marking ◼ Firing of a transition t in a marking is an atomic operation state transition of form (1, 0) → (0, 1) p1 : input place p2 : output place p1 p2 t1
Fire(cont) Firing a transition results in two things 1. Subtracting one token from the marking of any place p for every arc connecting p to t Adding one token to the marking of any place p for every arc connecting t to p
Fire (cont.) ◼ Firing a transition results in two things: 1. Subtracting one token from the marking of any place p for every arc connecting p to t 2. Adding one token to the marking of any place p for every arc connecting t to p
Firing example 2H,+O2→2H2O 2 2 H2○
Firing example 2H2 + O2 → 2H2O H2 O2 H2O t 2 2
Firing example 2H,+O2→2H2O 2 2 H2○
Firing example 2H2 + O2 → 2H2O H2 O2 H2O t 2 2