proposition: Lemma transdef_ord_unique p f1 f2: (forall x, ordinalp x -> transdef_ord_prop p f1 x) -> (forall x, ordinalp x -> transdef_ord_prop p f2 x) -> f1 =1o f2.
proof: Proof. move => H1 H2; apply:least_ordinal2' => y oy yp. by rewrite (H1 y oy) (H2 y oy);f_equal; apply: Lg_exten. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)