# HG changeset patch # User Kevin Walker # Date 1283042060 25200 # Node ID 4e4b6505d9ef4990d4e5101e852f1dfc6d202778 # Parent edf8798ef4775eae2d99605e872dc585b36c54ee starting to finish fiber bundle stuff diff -r edf8798ef477 -r 4e4b6505d9ef text/a_inf_blob.tex --- a/text/a_inf_blob.tex Fri Aug 27 15:36:21 2010 -0700 +++ b/text/a_inf_blob.tex Sat Aug 28 17:34:20 2010 -0700 @@ -227,36 +227,77 @@ Theorem \ref{thm:product} extends to the case of general fiber bundles \[ - F \to E \to Y . + F \to E \to Y , \] -We outline one approach here and a second in \S \ref{xyxyx}. +an indeed even to the case of general maps +\[ + M\to Y . +\] +We outline two approaches to these generalizations. +The first is somewhat tautological, while the second is more amenable to +calculation. 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 $Y$. 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 $\bc_*(p^*(E))$. +assign to $p:D\to Y$ the blob complex $\bc_*(p^*(E))$, if $\dim(D) = k$, +or the fields $\cE(p^*(E))$, if $\dim(D) < k$. +($p^*(E)$ 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 that +\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 \[ \bc_*(E) \simeq \cl{\cF_E}(Y) . \] - -\nn{remark further that this still works when the map is not even a fibration?} - -\nn{put this later} +\qed +\end{thm} -\nn{The second approach: Choose a decomposition $Y = \cup X_i$ +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 $\dim(Y) = k$. +Call a map $D^j\to Y$ ``good" with respect to $M$ if the fibered product +$D\widetilde{\times} M$ is a manifold of dimension $n-k+j$ with a collar structure along the boundary of $D$. +(If $D\to Y$ is an embedding then $D\widetilde{\times} M$ is just the part of $M$ +lying above $D$.) +We can define a $k$-category $\cF_M$ based on maps of balls into $Y$ which a re good with respect to $M$. +We can again adapt the homotopy colimit construction to +get a chain complex $\cl{\cF_M}(Y)$. +The proof of Theorem \ref{thm:product} again goes through essentially unchanged +to show that +\begin{thm} +Let $M \to Y$ be a map of manifolds and let $\cF_M$ be the $k$-category over $Y$ defined above. +Then +\[ + \bc_*(M) \simeq \cl{\cF_M}(Y) . +\] +\qed +\end{thm} + + +\medskip + +In the second approach we use a decorated colimit (as in \S \ref{ssec:spherecat}) +and various sphere modules based on $F \to E \to Y$ +or $M\to Y$, instead of an undecorated colimit with fancier $k$-categories over $Y$. +Information about the specific map to $Y$ has been taken out of the categories +and put into sphere modules and decorations. + +Let $F \to E \to Y$ be a fiber bundle as above. +Choose a decomposition $Y = \cup X_i$ such that the restriction of $E$ to $X_i$ is a product $F\times X_i$. -Choose the product structure as well. -To each codim-1 face $D_i\cap D_j$ we have a bimodule ($S^0$-module). +\nn{resume revising here} +Choose the product structure (trivialization of the bundle restricted to $X_i$) as well. +To each codim-1 face $X_i\cap X_j$ we have a bimodule ($S^0$-module). And more generally to each codim-$j$ face we have an $S^{j-1}$-module. Decorate the decomposition with these modules and do the colimit. -} + \nn{There is a version of this last construction for arbitrary maps $E \to Y$ (not necessarily a fibration). @@ -264,6 +305,11 @@ +Note that Theorem \ref{thm:gluing} can be viewed as a special case of this one. +Let $X_1$ and $X_2$ be $n$-manifolds + + + \subsection{A gluing theorem} \label{sec:gluing} @@ -406,12 +452,4 @@ \nn{maybe should also mention version where we enrich over spaces rather than chain complexes;} -\medskip -\hrule -\medskip -\nn{to be continued...} -\medskip -\nn{still to do: general maps} - -