Definition binop_int (sem: int -> int -> int) (x y: aval) :=
match x, y with I n, I m => I (sem n m) | _, _ => ntop2 x y end.

Lemma binop_int_sound:
forall sem v x w y,
vmatch v x -> vmatch w y ->
vmatch (match v, w with Vint i, Vint j => Vint(sem i j) | _, _ => Vundef end) (binop_int sem x y).