+ * mem.spin: Promela code to validate memory barriers with out-of-order memory
+ * and out-of-order instruction scheduling.
+ *
+ * Algorithm verified :
+ *
+ * alpha = 0;
+ * beta = 0;
+ * x = 1;
+ * y = 1;
+ *
+ * Process A Process B
+ * alpha = 1; beta = 1;
+ * mb(); mb();
+ * x = beta; y = alpha;
+ *
+ * if x = 0, then y != 0
+ * if y = 0, then x != 0