1C SB+poonceonces 2 3{} 4 5P0(int *x, int *y) 6{ 7 int r0; 8 9 WRITE_ONCE(*x, 1); 10 r0 = READ_ONCE(*y); 11} 12 13P1(int *x, int *y) 14{ 15 int r0; 16 17 WRITE_ONCE(*y, 1); 18 r0 = READ_ONCE(*x); 19} 20 21exists (0:r0=0 /\ 1:r0=0) 22