Hint Resolve set_incr: ty.

(* Specifications: *)
Lemma set_sound:
forall te x ty e e', set e x ty = OK e' -> satisf te e' -> te x = ty.
Lemma set_list_incr:
forall te xl tyl e e', set_list e xl tyl = OK e' -> satisf te e' -> satisf te e.
Lemma set_sound:
forall te x ty e e', set e x ty = OK e' -> satisf te e' -> te x = ty.
Lemma set_list_incr:
forall te xl tyl e e', set_list e xl tyl = OK e' -> satisf te e' -> satisf te e.