Exercises on Petri Net Analysis

Please refer to the lectures notes: Introduction to
Petri Nets.

  https://people.cs.pitt.edu/~chang/365/2petri/p1.htm

(1) Referring to Figure 1, suppose the initial marking is:
(1,0,0,0,0,0,0), what will be the marking after one
firing?

Answer: (0,1,1,0,0,0,0)

(2) What will be the markings after two firings?

Answer: (1,0,1,0,0,0,0) or (1,0,0,0,0,1,0)

(3) Will (1,0,0,1,0,0) be one of the markings after
three firings?

Answer: no.

(4) Referring to the figure on deadlocked Petri net:
  https://people.cs.pitt.edu/~chang/365/2petri/p7.htm

Is the marked Petri net as shown currently in a deadlock?

Answer: no.

(5) What would make the above marked Petri net entering
a deadlock?

Answer1: When both transitions (t1) and (t2) have fired.

Answer2: When both tokens have advanced to (pa2) and (pb2).