fact: Definition isDivRig_islunit_x0 {X : rig} (is : isDivRig X) : islunit (isDivRig_plus is) (isDivRig_zero is) := riglunax1 X.
imports: UniMath.Foundations.Sets UniMath.Algebra.RigsAndRings UniMath.Algebra.Domains_and_Fields UniMath.MoreFoundations.Tactics