diff -r 45ffa363a8c8 -r fcd380e21e7c text/a_inf_blob.tex --- a/text/a_inf_blob.tex Wed Oct 12 17:50:00 2011 -0700 +++ b/text/a_inf_blob.tex Thu Oct 13 10:54:06 2011 -0700 @@ -265,16 +265,15 @@ We can generalize the definition of a $k$-category by replacing the categories of $j$-balls ($j\le k$) with categories of $j$-balls $D$ equipped with a map $p:D\to Y$ (c.f. \cite{MR2079378}). -Call this a $k$-category over $Y$. +Call this a {\it $k$-category over $Y$}. A fiber bundle $F\to E\to Y$ gives an example of a $k$-category over $Y$: -assign to $p:D\to Y$ the blob complex $\bc_*(p^*(E))$, if $\dim(D) = k$, -or the fields $\cE(p^*(E))$, if $\dim(D) < k$. +assign to $p:D\to Y$ the blob complex $\bc_*(p^*(E))$, when $\dim(D) = k$, +or the fields $\cE(p^*(E))$, when $\dim(D) < k$. (Here $p^*(E)$ denotes the pull-back bundle over $D$.) Let $\cF_E$ denote this $k$-category over $Y$. We can adapt the homotopy colimit construction (based decompositions of $Y$ into balls) to get a chain complex $\cl{\cF_E}(Y)$. -The proof of Theorem \ref{thm:product} goes through essentially unchanged -to show the following result. + \begin{thm} Let $F \to E \to Y$ be a fiber bundle and let $\cF_E$ be the $k$-category over $Y$ defined above. Then @@ -284,6 +283,26 @@ \qed \end{thm} +\begin{proof} +The proof is nearly identical to the proof of Theorem \ref{thm:product}, so we will only give a sketch which +emphasizes the few minor changes that need to be made. + +As before, we define a map +\[ + \psi: \cl{\cF_E}(Y) \to \bc_*(E) . +\] +0-simplices of the homotopy colimit $\cl{\cF_E}(Y)$ are glued up to give an element of $\bc_*(E)$. +Simplices of positive degree are sent to zero. + +Let $G_* \sub \bc_*(E)$ be the image of $\psi$. +By Lemma \ref{thm:small-blobs}, $\bc_*(Y\times F; \cE)$ +is homotopic to a subcomplex of $G_*$. +We will define a homotopy inverse of $\psi$ on $G_*$, using acyclic models. +To each generator $a$ of $G_*$ we assign an acyclic subcomplex $D(a) \sub \cl{\cF_E}(Y)$ which consists of +0-simplices which map via $\psi$ to $a$, plus higher simplices (as described in the proof of Theorem \ref{thm:product}) +which insure that $D(a)$ is acyclic. +\end{proof} + We can generalize this result still further by noting that it is not really necessary for the definition of $\cF_E$ that $E\to Y$ be a fiber bundle. Let $M\to Y$ be a map, with $\dim(M) = n$ and $\dim(Y) = k$.