fact: Definition is_torsor {G:gr} (X:Action G) := nonempty X × ∏ x:X, isweq (right_mult x).
imports: UniMath.Foundations.All UniMath.MoreFoundations.Propositions UniMath.MoreFoundations.Notations UniMath.MoreFoundations.Univalence UniMath.MoreFoundations.Tactics UniMath.Algebra.Monoids UniMath.Algebra.Groups UniMath.Combinatorics.OrderedSets