diff -r c3c8fb292934 -r ae5fd0a7a8a3 text/deligne.tex --- a/text/deligne.tex Sun Jul 18 11:07:47 2010 -0600 +++ b/text/deligne.tex Sun Jul 18 18:23:31 2010 -0600 @@ -2,14 +2,11 @@ \section{Higher-dimensional Deligne conjecture} \label{sec:deligne} -In this section we -sketch -\nn{revisit ``sketch" after proof is done} -the proof of a higher dimensional version of the Deligne conjecture -about the action of the little disks operad on Hochschild cohomology. +In this section we prove a higher dimensional version of the Deligne conjecture +about the action of the little disks operad on Hochschild cochains. The first several paragraphs lead up to a precise statement of the result (Theorem \ref{thm:deligne} below). -Then we sketch the proof. +Then we give the proof. \nn{Does this generalization encompass Kontsevich's proposed generalization from \cite[\S2.5]{MR1718044}, that (I think...) the Hochschild homology of an $E_n$ algebra is an $E_{n+1}$ algebra? -S} @@ -23,14 +20,14 @@ C_*(LD_k)\otimes \overbrace{Hoch^*(C, C)\otimes\cdots\otimes Hoch^*(C, C)}^{\text{$k$ copies}} \to Hoch^*(C, C) . \] -Here $LD_k$ is the $k$-th space of the little disks operad, and $Hoch^*(C, C)$ denotes Hochschild +Here $LD_k$ is the $k$-th space of the little disks operad and $Hoch^*(C, C)$ denotes Hochschild cochains. The little disks operad is homotopy equivalent to the -(transversely orient) fat graph operad -\nn{need ref, or say more precisely what we mean}, +(transversely oriented) fat graph operad +(see below), and Hochschild cochains are homotopy equivalent to $A_\infty$ endomorphisms of the blob complex of the interval, thought of as a bimodule for itself. -\nn{need to make sure we prove this above}. +(see \S\ref{ss:module-morphisms}). So the 1-dimensional Deligne conjecture can be restated as \[ C_*(FG_k)\otimes \hom(\bc^C_*(I), \bc^C_*(I))\otimes\cdots @@ -73,7 +70,7 @@ More specifically, an $n$-dimensional fat graph ($n$-FG for short) consists of: \begin{itemize} -\item ``Upper" $n$-manifolds $M_0,\ldots,M_k$ and ``lower" $n$-manifolds $N_0,\ldots,N_k$, +\item ``Lower" $n$-manifolds $M_0,\ldots,M_k$ and ``upper" $n$-manifolds $N_0,\ldots,N_k$, with $\bd M_i = \bd N_i = E_i$ for all $i$. We call $M_0$ and $N_0$ the outer boundary and the remaining $M_i$'s and $N_i$'s the inner boundaries. @@ -110,7 +107,8 @@ (See Figure \ref{xdfig3}.) \begin{figure}[t] $$\mathfig{.4}{deligne/dfig3a} \to \mathfig{.4}{deligne/dfig3b} $$ -\caption{Conjugating by a homeomorphism}\label{xdfig3} +\caption{Conjugating by a homeomorphism +\nn{change right $R_i$ to $R'_i$}}\label{xdfig3} \end{figure} \item If $M_i = M'_i \du M''_i$ and $N_i = N'_i \du N''_i$ (and there is a compatible disjoint union of $\bd M = \bd N$), we can replace @@ -170,10 +168,10 @@ with contractible fibers. (The fibers correspond to moving the $D_i$'s in the $x_{n+1}$ direction without changing their ordering.) -\nn{issue: we've described this by varying the $R_i$'s, but above we emphasize varying the $f_i$'s. -does this need more explanation?} +%\nn{issue: we've described this by varying the $R_i$'s, but above we emphasize varying the $f_i$'s. +%does this need more explanation?} -Another familiar subspace of the $n$-FG operad is $\Homeo(M\to N)$, which corresponds to +Another familiar subspace of the $n$-FG operad is $\Homeo(M_0\to N_0)$, which corresponds to case $k=0$ (no holes). \medskip @@ -194,7 +192,7 @@ \cdots \stackrel{\id\ot\alpha_k}{\to} \bc_*(R_k\cup N_k) \stackrel{f_k}{\to} \bc_*(N_0) \] -(Recall that the maps $\id\ot\alpha_i$ were defined in \nn{need ref}.) +(Recall that the maps $\id\ot\alpha_i$ were defined in \S\ref{ss:module-morphisms}s.) \nn{need to double check case where $\alpha_i$'s are not closed.} It is easy to check that the above definition is compatible with the equivalence relations and also the operad structure. @@ -237,8 +235,10 @@ $FG^n_{\overline{M}, \overline{N}}$ is constructed from the various $P$'s. This in turn follows easily from the fact that the actions of $C_*(\Homeo(\cdot\to\cdot))$ are local (compatible with gluing) and associative. - -\nn{should add some detail to above} +%\nn{should add some detail to above} \end{proof} -\nn{maybe point out that even for $n=1$ there's something new here.} +We note that even when $n=1$, the above theorem goes beyond an action of the little disks operad. +$M_i$ could be a disjoint union of intervals, and $N_i$ could connect the end points of the intervals +in a different pattern from $M_i$. +The genus of the fat graph could be greater than zero.