Ltac do_map_arg :=
match goal with |- ?a = ?b =>
match a with context [map ?x _] =>
match b with context [map ?y _] => replace y with x; auto end end end.

Lemma YES_join_full':
forall loc k P m1 m2 m3, join m1 m2 m3 -> m1@loc = YES pfullshare k P ->
m3 @ loc = YES pfullshare k P.