Hint Rewrite canon3 using check_nonlocal : canon.
Hint Rewrite canon3b using check_nonlocal : canon.
Hint Rewrite canon7 using check_nonlocal : canon.
Hint Rewrite <- (@sepcon_assoc (environ->mpred) _) : canon.

Lemma canon6c: forall Q R,
nonlocal Q ->
(Q && prop R) = prop R && Q.