2021/12/28 by Yaddaden, Khalef · 1 citation
#Algebraic Geometry (math.AG) #FOS: Mathematics
paper · doi:10.48550/arxiv.2112.14140
Racinet studied the scheme associated with the double shuffle and regularization relations between multiple polylogarithm values at Nth roots of unity and constructed a group scheme attached to the situation; he also showed it to be the specialization for G=μN of a group scheme DMR0G attached to a finite abelian group G. Then, Enriquez and Furusho proved that DMR0G can be essentially identified with the stabilizer of a coproduct element arising in Racinet's theory with respect to the action of a group of automorphisms of a free Lie algebra attached to G. We reformulate Racinet's construction in terms of crossed products. Racinet's coproduct can then be identified with a coproduct ΔMG defined on a module MG over an algebra WG, which is equipped with its own coproduct ΔWG, and the group action on MG extends to a compatible action of WG. We then show that the stabilizer of ΔMG, hence DMR0G, is contained in the stabilizer of ΔWG. This yields an explicit group scheme containing DMR0G, which we also express in the Racinet formalism.