Lemma grfromltunel (X : gr) {R : hrel X} (is : isbinophrel R) {x : X} (isg : R 1 x) : R (x^-1) 1. Proof. assert (r := (pr1 is) _ _ (x^-1) isg). rewrite (grlinvax X x) in r. rewrite (runax X _) in r. apply r. Defined.
Require Import UniMath.MoreFoundations.Subtypes.