diff -r d450abe6decb -r bd9538de8248 text/ncat.tex --- a/text/ncat.tex Fri May 13 21:16:40 2011 -0700 +++ b/text/ncat.tex Sat May 14 11:42:48 2011 -0700 @@ -1068,6 +1068,7 @@ (To start the induction, we define $\cl\cC(M)$, where $M = \du_a P_a$ is a 0-manifold and each $P_a$ is a 0-ball, to be $\prod_a \cC(P_a)$.) We also assume, inductively, that we have gluing and restriction maps for colimits of $k{-}1$-manifolds. +Gluing and restriction maps for colimits of $k$-manifolds will be defined later in this subsection. Let $\du_a X_a = M_0\to\cdots\to M_m = W$ be a ball decomposition compatible with $x$. Let $\bd M_i = N_i \cup Y_i \cup Y'_i$, where $Y_i$ and $Y'_i$ are glued together to produce $M_{i+1}$. @@ -1088,6 +1089,7 @@ along $\bd Y_1$ and $\bd Y'_1$, and that the restrictions to $\cl\cC(Y_1)$ and $\cl\cC(Y'_1)$ agree (with respect to the identification of $Y_1$ and $Y'_1$ provided by the gluing map). The $i$-th condition is defined similarly. +Note that these conditions depend on on the boundaries of elements of $\prod_a \cC(X_a)$. We define $\psi_{\cC;W}(x)$ to be the subset of $\prod_a \cC(X_a)$ which satisfies the above conditions for all $i$ and also all @@ -1097,52 +1099,26 @@ Rather than try to prove a similar result for arbitrary permissible decompositions, we instead require compatibility with all ways of gluing up the decomposition.) -If $x$ is a refinement of $y$, the map $\psi_{\cC;W}(x) \to \psi_{\cC;W}(y)$ is given by the composition maps of $\cC$. - - -\nn{to do: define splittability and restrictions for colimits} - -\noop{ %%%%%%%%%%%%%%%%%%%%%%% -For pedagogical reasons, let us first consider the case of a decomposition $y$ of $W$ -which is a nice, non-pathological cell decomposition. -Then each $k$-ball $X$ of $y$ has its boundary decomposed into $k{-}1$-balls, -and, as described above, we have a subset $\cC(X)\spl \sub \cC(X)$ of morphisms whose boundaries -are splittable along this decomposition. +If $x$ is a refinement of $y$, the map $\psi_{\cC;W}(x) \to \psi_{\cC;W}(y)$ +is given by the composition maps of $\cC$. +This completes the definition of the functor $\psi_{\cC;W}$. -We can now -define the functor $\psi_{\cC;W} : \cell(W) \to \Set$ as follows. -For a decomposition $x = \bigsqcup_a X_a$ in $\cell(W)$, $\psi_{\cC;W}(x)$ is the subset -\begin{equation} -%\label{eq:psi-C} - \psi_{\cC;W}(x) \sub \prod_a \cC(X_a)\spl -\end{equation} -where the restrictions to the various pieces of shared boundaries amongst the cells -$X_a$ all agree (this is a fibered product of all the labels of $n$-cells over the labels of $n{-}1$-cells). -If $x$ is a refinement of $y$, the map $\psi_{\cC;W}(x) \to \psi_{\cC;W}(y)$ is given by the composition maps of $\cC$. - -In general, $y$ might be more general than a cell decomposition -(see Example \ref{sin1x-example}), so we must define $\psi_{\cC;W}$ in a more roundabout way. -\nn{...} - -\begin{defn} -Define the functor $\psi_{\cC;W} : \cell(W) \to \Set$ as follows. -\nn{...} -If $x$ is a refinement of $y$, the map $\psi_{\cC;W}(x) \to \psi_{\cC;W}(y)$ is given by the composition maps of $\cC$. -\end{defn} -} % end \noop %%%%%%%%%%%%%%%%%%%%%%% +Note that we have constructed, at the last stage of the above procedure, +a map from $\psi_{\cC;W}(x)$ to $\cl\cC(\bd M_m) = \cl\cC(\bd W)$. If $k=n$ in the above definition and we are enriching in some auxiliary category, we need to say a bit more. We can rewrite the colimit as -\begin{equation} \label{eq:psi-CC} +\[ % \begin{equation} \label{eq:psi-CC} \psi_{\cC;W}(x) \deq \coprod_\beta \prod_a \cC(X_a; \beta) , -\end{equation} -where $\beta$ runs through labelings of the $k{-}1$-skeleton of the decomposition -(which are compatible when restricted to the $k{-}2$-skeleton), and $\cC(X_a; \beta)$ -means the subset of $\cC(X_a)$ whose restriction to $\bd X_a$ agress with $\beta$. +\] % \end{equation} +where $\beta$ runs through +boundary conditions on $\du_a X_a$ which are compatible with gluing as specified above +and $\cC(X_a; \beta)$ +means the subset of $\cC(X_a)$ whose restriction to $\bd X_a$ agrees with $\beta$. If we are enriching over $\cS$ and $k=n$, then $\cC(X_a; \beta)$ is an object in -$\cS$ and the coproduct and product in Equation \ref{eq:psi-CC} should be replaced by the approriate +$\cS$ and the coproduct and product in the above expression should be replaced by the appropriate operations in $\cS$ (e.g. direct sum and tensor product if $\cS$ is Vect). Finally, we construct $\cl{\cC}(W)$ as the appropriate colimit of $\psi_{\cC;W}$: @@ -1244,6 +1220,12 @@ there are well-defined maps $\cl{\cC}(W)\to\cl{\cC}(\bd W)$, and that these maps comprise a natural transformation of functors. + + +\nn{to do: define splittability and restrictions for colimits} + + + \begin{lem} \label{lem:colim-injective} Let $W$ be a manifold of dimension less than $n$. Then for each