{ Petri net generated by APT for net exercise 2.1 solution }

PLACE
available, mailbox, received, resting, waiting, written;

MARKING
	available	: 5,
	resting	: 1,
	waiting	: 1;

TRANSITION read
CONSUME
	received	: 1;
PRODUCE
	waiting	: 1;

TRANSITION receive
CONSUME
	mailbox	: 1,
	waiting	: 1;
PRODUCE
	available	: 1,
	received	: 1;

TRANSITION send
CONSUME
	available	: 1,
	written	: 1;
PRODUCE
	resting	: 1,
	mailbox	: 1;

TRANSITION write
CONSUME
	resting	: 1;
PRODUCE
	written	: 1;