. Please consider the following mutual exclusion algorithm that uses the shared variables y1 and y2 (initially both 0).
Process P1:
while true do
. . . noncritical section . . .
y1 := y2 + 1;
wait until (y2 = 0) ∨ (y1 < y2)
. . . critical section . . .
y1 := 0;
od
Process P2:
while true do
. . . noncritical section . . .
y2 := y1 + 1;
wait until (y1 = 0) ∨ (y2 < y1)
. . . critical section . . .
y2 := 0;
od
Please answer following questions:
a) Give the program graph representations of both processes. (A pictorial representation suffices.)
b) Give the reachable part of the transition system of P1 || P2 where y1 ≤ 2 and y2 ≤ 2.
c) Describe an execution that shows that the entire transition system is infinite.
d) Check whether the algorithm indeed ensures mutual exclusion.
e) Check whether the algorithm never reaches a state in which both processes are mutually waiting for
each other.
f) Is it possible that a process that wants to enter the critical section has to wait ad infinitum?

Ashielded metal arc-welding operation is accomplished in a work cell by a fitter and a welder. the fitter takes 5.5 min to load components into the welding fixture at the beginning of the work cycle, and 1.5 min to unload the completed weldment at the end of the cycle. the total ength of the weld seams 1200 mm, and the travel speed used by the welder averages 300 mm/min. every 600 mm of seam length, the welding stick must be changed, which takes 0.8 min. while the fitter is working, the welder is idle (resting): and while the welder is working the fitter is idle. (a) determine the average arc-on time as a fraction of the work cycle time. (b) how much improvement in arc-on time would result if the welder used flux-cored arc welding (manually operated), given that the spool of weld wire must be changed every 10 weldments, and it takes the welder 5.0 min to accomplish the change? (c) what are the production rates for these two cases (weldments completed per hour)? attach your work and solutions.