Consider each step in the entry and exit sections. There is an assignment of intention to enter, P1. There is an assignment of whose turn it is, P2. There is a spin wait with two non-atomic tests (test for other process intention P3a, and for other process turn, P3b. Then there is the critical section, P4. Then there is the exit relinquishing of the intention, P5. This numbering may be different from Silberschatz's slides. Consider the corresponding steps in the other process Q1, ... Q5. Choose a random interleaving of Ps and Qs. P1, ..., P5 and Q1, ..., Q5 must be ordered within each P sequence and Q sequence, but the ordering of P's relative to Q's can be any possible, e. g. P1, P2, Q1, P3a, Q2, Q3a, Q3b, ... . Also, P4, P5 and Q4, Q5 are constrained to occur only if the conditions for P3a, b and Q3a, b obtain. Show that for your random ordering that there is mutual exclusion, i. e., P4 and Q4 are not adjacent.