{A} `{Is1Gpd A} {x y : A} {p : x $-> y} {q : y $-> x} (r : Id _ $== p $o q) : p^$ $== q. Proof. refine ((cat_idr p^$)^$ $@ (p^$ $@L r) $@ _). apply gpd_V_hh. Defined.
Require Import Basics.Overture Basics.Tactics.