{G : Group} (g h : G) (p : g * h = h * g) : g * (-h) = (-h) * g. Proof. apply grp_moveR_gV. rhs_V apply simple_associativity. by apply grp_moveL_Vg. Defined.
Require Import Basics Types HProp HFiber HSet. Require Import Homotopy.IdentitySystems. Require Import (notations) Classes.interfaces.canonical_names. Require Import Pointed.Core. Require Import WildCat. Require Import Spaces.Nat.Core Spaces.Int. Require Import Truncations.Core.