Consider the following 3 processes:
P
St1
P(x1)
St2
P(x2)
St3
V(x2)
St4
V(x1)
St5
Q
St6
P(x3)
St7
P(x2)
St8
V(x3)
St9
V(x2)
St10
R
St11
P(x2)
St12
P(x3)
St13
V(x2)
St14
P(x1)
St15
V(x3)
St16
V(x1)
St17
P, Q, R are not in loops. Sempahores x1, x2... are initialized to 1.
The "combined" state of the three processes can be depicted by a 3- tuple. If the system state is
<<St1, St7, St15>>, this denotes process P is executing St1, process Q is executing St7 and
process R is executing St15 concurrently.
If <<St1, St7, St15>> is a valid state, it means that Process P can execute line number St1, at the
same time process Q can execute St7, and at the same time process R can also execute St15. "At
the same time" here means concurrently.