Section STABILITY.
Variable CS: compspecs.
Variables Delta Delta': tycontext.
Hypothesis extends: tycontext_sub Delta Delta'.
Definition typeof_temp (Delta: tycontext) (id: ident) : option type :=
match (temp_types Delta) ! id with
| Some t => Some t
| None => None
end.

Lemma typeof_temp_sub:
forall i t,
typeof_temp Delta i = Some t ->
typeof_temp Delta' i = Some t.