Enriquez, B.; Gavarini, F.
(Symmetry, Integrability and Geometry: Methods and Applications, 2006)
We prove that the logarithm of a group-like element in a free algebra coincides with its image by a certain linear map. We use this result and the formula of Le and Murakami for the Knizhnik-Zamolodchikov (KZ) associator ...