fact: Definition eq_sigT_hprop_iff {A P} (P_hprop : forall (x : A) (p q : P x), p = q) (u v : { a : A & P a }) : u = v <-> (u.1 = v.1) := conj (fun p => f_equal (@projT1 _ _) p) (eq_sigT_hprop P_hprop u v).
imports: Notations Ltac Datatypes Logic