diff -r 675f53735445 -r 1d76e832d32f text/a_inf_blob.tex --- a/text/a_inf_blob.tex Fri Jun 04 17:00:18 2010 -0700 +++ b/text/a_inf_blob.tex Fri Jun 04 17:15:53 2010 -0700 @@ -16,7 +16,8 @@ \medskip An important technical tool in the proofs of this section is provided by the idea of `small blobs'. -Fix $\cU$, an open cover of $M$. Define the `small blob complex' $\bc^{\cU}_*(M)$ to be the subcomplex of $\bc_*(M)$ of all blob diagrams in which every blob is contained in some open set of $\cU$. +Fix $\cU$, an open cover of $M$. +Define the `small blob complex' $\bc^{\cU}_*(M)$ to be the subcomplex of $\bc_*(M)$ of all blob diagrams in which every blob is contained in some open set of $\cU$. \nn{KW: We need something a little stronger: Every blob diagram (even a 0-blob diagram) is splittable into pieces which are small w.r.t.\ $\cU$. If field have potentially large coupons/boxes, then this is a non-trivial constraint. On the other hand, we could probably get away with ignoring this point. @@ -46,11 +47,14 @@ \nn{need to settle on notation; proof and statement are inconsistent} \begin{thm} \label{product_thm} -Given a topological $n$-category $C$ and a $n{-}k$-manifold $F$, recall from Example \ref{ex:blob-complexes-of-balls} that there is an $A_\infty$ $k$-category $C^{\times F}$ defined by +Given a topological $n$-category $C$ and a $n{-}k$-manifold $F$, recall from +Example \ref{ex:blob-complexes-of-balls} that there is an $A_\infty$ $k$-category $C^{\times F}$ defined by \begin{equation*} C^{\times F}(B) = \cB_*(B \times F, C). \end{equation*} -Now, given a $k$-manifold $Y$, there is a homotopy equivalence between the `old-fashioned' blob complex for $Y \times F$ with coefficients in $C$ and the `new-fangled' (i.e.\ homotopy colimit) blob complex for $Y$ with coefficients in $C^{\times F}$: +Now, given a $k$-manifold $Y$, there is a homotopy equivalence between the `old-fashioned' +blob complex for $Y \times F$ with coefficients in $C$ and the `new-fangled' +(i.e.\ homotopy colimit) blob complex for $Y$ with coefficients in $C^{\times F}$: \begin{align*} \cB_*(Y \times F, C) & \htpy \cB_*(Y, C^{\times F}) \end{align*} @@ -305,7 +309,8 @@ Let $\cT$ denote the chain complex $\bc(X_1) \otimes_{\bc(Y), J} \bc(X_2)$. Recall that this is a homotopy colimit based on decompositions of the interval $J$. -We define a map $\psi:\cT\to \bc_*(X)$. On filtration degree zero summands it is given +We define a map $\psi:\cT\to \bc_*(X)$. +On filtration degree zero summands it is given by gluing the pieces together to get a blob diagram on $X$. On filtration degree 1 and greater $\psi$ is zero. @@ -353,11 +358,18 @@ To simplify notation, let $\cT = \pi^\infty_{\leq n}(T)$. \begin{thm} \label{thm:map-recon} -The blob complex for $M$ with coefficients in the fundamental $A_\infty$ $n$-category for $T$ is quasi-isomorphic to singular chains on maps from $M$ to $T$. +The blob complex for $M$ with coefficients in the fundamental $A_\infty$ $n$-category for $T$ +is quasi-isomorphic to singular chains on maps from $M$ to $T$. $$\cB^\cT(M) \simeq C_*(\Maps(M\to T)).$$ \end{thm} \begin{rem} -Lurie has shown in \cite[Theorem 3.8.6]{0911.0018} that the topological chiral homology of an $n$-manifold $M$ with coefficients in a certain $E_n$ algebra constructed from $T$ recovers the same space of singular chains on maps from $M$ to $T$, with the additional hypothesis that $T$ is $n-1$-connected. This extra hypothesis is not surprising, in view of the idea described in Example \ref{ex:e-n-alg} that an $E_n$ algebra is roughly equivalent data to an $A_\infty$ $n$-category which is trivial at all but the topmost level. Ricardo Andrade also told us about a similar result. +Lurie has shown in \cite[Theorem 3.8.6]{0911.0018} that the topological chiral homology +of an $n$-manifold $M$ with coefficients in a certain $E_n$ algebra constructed from $T$ recovers +the same space of singular chains on maps from $M$ to $T$, with the additional hypothesis that $T$ is $n-1$-connected. +This extra hypothesis is not surprising, in view of the idea described in Example \ref{ex:e-n-alg} +that an $E_n$ algebra is roughly equivalent data to an $A_\infty$ $n$-category which +is trivial at all but the topmost level. +Ricardo Andrade also told us about a similar result. \end{rem} \nn{proof is again similar to that of Theorem \ref{product_thm}. should probably say that explicitly}