Definition commringfracinv1int (X : commring) (S : @subabmonoid (ringmultabmonoid X)) : X × S → X × S := λ xs, -1 * pr1 xs ,, pr2 xs.
Require Import UniMath.Algebra.Groups. Require Import UniMath.MoreFoundations.Sets. Require Import UniMath.MoreFoundations.Orders.