fact: Definition abgr_Kernel_subabgr_issubgr {A B : abgr} (f : monoidfun A B) : issubgr (abgr_kernel_hsubtype f).
imports: UniMath.MoreFoundations.Orders UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.Subtypes UniMath.Algebra.BinaryOperations UniMath.Algebra.Monoids