fact: Definition free_gr_hrel (X : hSet) : hrel (free_monoid (setcoprod X X)) := λ g h, ∃ x, x::coprodcomm X X x::[] = g × [] = h.
imports: UniMath.MoreFoundations.Subtypes UniMath.MoreFoundations.Sets UniMath.Algebra.Monoids UniMath.Algebra.Groups UniMath.Algebra.IteratedBinaryOperations UniMath.Combinatorics.Lists