Arguments validO [K T U j k ts1 ts2 f1 f2] _ _.
Example ex0 (x y z : nat) (v1 v2 : nat) h:
valid (Unit \+ y \\-> v1 \+ h \+ x \\-> v1) ->
valid (x \\-> v2 \+ Unit).
Canonical start j k ts1 ts2 f2 := RForm (@start_pf j k ts1 ts2 f2).
End ValidX.
Module Exports.
Canonical equate.
Canonical start.
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 *)

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