Primitive Idea for Access History
		Serial    read(l), write(l) Simplest parallel program without nested parallelism    Two parallel read records, one write record Language structure like Cilk    read: max level of parallelism, one write record Q: Is it possible to keep only two read records for each shared location in Cilk Parallel Nondeterminator?    Keep two parallel read records with highest level of LCA in parent child spawn tree.