Section Exports.
Variables (K : ordType) (T : Type) (U : union_map_class K T).
Implicit Types (j : ctx U) (ts : seq (term T)).
Notation form := Syntactify.form.
Notation untag := Syntactify.untag.
(* the main lemma; note how the boolean component of rform is set to true *)

Lemma validX m j ts1 (f1 : form (empx U) j ts1) (g: rform j ts1 m true) :
valid (untag f1) -> valid (unpack (pivot g)).