Scheme context_ind2 := Minimality for context Sort Prop
with contextlist_ind2 := Minimality for contextlist Sort Prop.
Combined Scheme context_contextlist_ind from context_ind2, contextlist_ind2.

Lemma invert_expr_context:
(forall from to C, context from to C ->
forall a m,
invert_expr_prop a m ->
invert_expr_prop (C a) m)
/\(forall from C, contextlist from C ->
forall a m,
invert_expr_prop a m ->
~exprlist_all_values (C a)).