{ Petri net generated by APT for net exercise 4.3 solution }

PLACE
s1, s1p, s2, s2p;

MARKING
	s1	: 1,
	s2p	: 2;

TRANSITION t1
CONSUME;
PRODUCE
	s1	: 1;

TRANSITION t2
CONSUME
	s1	: 1;
PRODUCE
	s2	: 1;

TRANSITION t3
CONSUME
	s2	: 1;
PRODUCE
	s1	: 1;

TRANSITION t4
CONSUME
	s2	: 1;
PRODUCE;

TRANSITION ts1
CONSUME
	s1p	: 1,
	s1	: 1;
PRODUCE;

TRANSITION ts2
CONSUME
	s2	: 1,
	s2p	: 1;
PRODUCE;