Definition permMapJoin (pmap1 pmap2 pmap3: access_map) :=
forall b ofs,
permjoin ((pmap1 !! b) ofs) ((pmap2 !! b) ofs) ((pmap3 !! b) ofs).

Lemma perm_order_valid_block:
forall pmap m b ofs p
(Hperm: Mem.perm_order'' (pmap !! b ofs) (Some p))
(Hlt: permMapLt pmap (getMaxPerm m)),
Mem.valid_block m b.