Definition juicy_mem_core (j: juicy_mem) : rmap := core (m_phi j).

Lemma valid_access_None: forall m ch b b' ofs ofs' p, Mem.valid_access m ch b ofs p -> adr_range (b, ofs) (size_chunk ch) (b', ofs') -> access_at m (b', ofs') Cur = None -> False.