fact: Definition islinear {R : ring} {M N : module R} (f : M -> N) := ∏ r : R, ∏ x : M, f (r * x) = r * (f x).
imports: UniMath.MoreFoundations.Tactics UniMath.Algebra.RigsAndRings UniMath.Algebra.Groups UniMath.Algebra.Monoids