Local Hint Resolve perm_valid_block: mem.
Remark perm_order_dec:
forall p1 p2, {perm_order p1 p2} + {~perm_order p1 p2}.

Theorem range_perm_cur:
forall m b lo hi k p,
range_perm m b lo hi Cur p -> range_perm m b lo hi k p.