C LB+poonceonces {} P0(int *x, int *y) { int r0; r0 = READ_ONCE(*x); WRITE_ONCE(*y, 1); } P1(int *x, int *y) { int r0; r0 = READ_ONCE(*y); WRITE_ONCE(*x, 1); } exists (0:r0=1 /\ 1:r0=1)