Tuesday, 13 September 2011

operads - Are G_infinity algebras B_infinity? Vice versa?

What is the relationship between Ginfty (homotopy Gerstenhaber) and Binfty algebras?



In Getzler & Jones "Operads, homotopy algebra, and iterated integrals for double loop spaces" (a paper I don't well understand) a Binfty algebra is defined to be a graded vector space V together with a dg-bialgebra structure on BV=oplusigeq0(V[1])otimesi, that is a square-zero, degree one coderivation delta of the canonical coalgebra structure (stopping here, we have defined an Ainfty algebra) and an associative multiplication m:BVotimesBVtoBV that is a morphism of coalgebras and such that delta is a derivation of m.



A Ginfty algebra is more complicated. The Ginfty operad is a dg-operad whose underlying graded operad is free and such that its cohomology is the operad controlling Gerstenhaber algebras. I believe that the operad of chains on the little 2-discs operad is a model for the Ginfty operad. Yes?



It is now known (the famous Deligne conjecture) that the Hochschild cochain complex of an associative algebra carries the structure of a Ginfty algebra. It also carries the structure of a Binfty algebra. Some articles discuss the Ginfty structure while others discuss the Binfty structure. So I wonder: How are these structures related in this case? In general?

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