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)).