+-------------------------+-------------------------+
| Process X:              | Process Y:              |
| private i;              | private i;              |
| for (i=0; i < n; i++) { | for (i=0; i < n; i++) { |
|    a[i] = f(i);         |    EntryY(R, S);        |
|    ExitX(R, S);         |    b[i]=g(a[i]);        |
| }                       | }                       |
+-------------------------+-------------------------+

+---------------+----------------+
| ExitX(R, S) { | EntryY(R, S) { |
|   P(S);       |   V(S);        |
|   V(R);       |   P(R);        |
| }             | }              |
+---------------+----------------+

+---------------+----------------+
| ExitX(R, S) { | EntryY(R, S) { |
|   V(R);       |   P(R);        |
|   P(S);       |   V(S);        |
| }             | }              |
+---------------+----------------+