--- a/blob to-do Thu May 12 21:42:34 2011 -0700
+++ b/blob to-do Fri May 13 20:52:18 2011 -0700
@@ -67,5 +67,7 @@
* lemma [inject 6.3.5?] assumes more splittablity than the axioms imply (?)
-* figure for example 3.1.2 (sin 1/z)
+* SCOTT: figure for example 3.1.2 (sin 1/z)
+* SCOTT: add vertical arrow to middle of figure 19 (decomp poset)
+
--- a/blob_changes_v3 Thu May 12 21:42:34 2011 -0700
+++ b/blob_changes_v3 Fri May 13 20:52:18 2011 -0700
@@ -12,12 +12,16 @@
- change to pitchfork notation for splittable subsets of fields
- added definition of collaring homeomorphism
- improved definition of bordism n-category
-- fixed definition of a refinement of a ball decomposition (intermediate manifolds should also be disjoiunt unions of balls)
+- fixed definition of a refinement of a ball decomposition (intermediate manifolds should also be disjoint unions of balls)
- added brief definition of monoidal n-categories
- fixed statement of compatibility of product morphisms with gluing
- added remark about manifolds which do not admit ball decompositions; restricted product theorem (7.1.1) to apply only to these manifolds
- added remarks about categories of defects
- clarified that the "cell complexes" in string diagrams are actually a bit more general
- added remark to insure that the poset of decompositions is a small category
+- rewrote definition of colimit (in "From Balls to Manifolds" subsection) to allow for more general decompositions; also added more details
+-
+
+
--- a/text/ncat.tex Thu May 12 21:42:34 2011 -0700
+++ b/text/ncat.tex Fri May 13 20:52:18 2011 -0700
@@ -936,7 +936,7 @@
Note in particular that the space for $k=1$ contains a copy of $\Diff(B^n)$, namely
the embeddings of a ``little" ball with image all of the big ball $B^n$.
(But note also that this inclusion is not
-necessarily a homotopy equivalence.)
+necessarily a homotopy equivalence.))
The operad $\cE\cB_n$ is homotopy equivalent to the standard framed little $n$-ball operad:
by shrinking the little balls (precomposing them with dilations),
we see that both operads are homotopic to the space of $k$ framed points
@@ -1001,7 +1001,7 @@
\medskip
-We will first define the ``decomposition" poset $\cell(W)$ for any $k$-manifold $W$, for $1 \leq k \leq n$.
+We will first define the {\it decomposition poset} $\cell(W)$ for any $k$-manifold $W$, for $1 \leq k \leq n$.
An $n$-category $\cC$ provides a functor from this poset to the category of sets,
and we will define $\cl{\cC}(W)$ as a suitable colimit
(or homotopy colimit in the $A_\infty$ case) of this functor.
@@ -1042,7 +1042,7 @@
\begin{defn}
The poset $\cell(W)$ has objects the permissible decompositions of $W$,
and a unique morphism from $x$ to $y$ if and only if $x$ is a refinement of $y$.
-See Figure \ref{partofJfig} for an example.
+See Figure \ref{partofJfig}.
\end{defn}
\begin{figure}[t]
@@ -1056,8 +1056,56 @@
An $n$-category $\cC$ determines
a functor $\psi_{\cC;W}$ from $\cell(W)$ to the category of sets
(possibly with additional structure if $k=n$).
-For pedagogical reasons, let us first the case where a decomposition $y$ of $W$ is a nice, non-pathological
-cell decomposition.
+Let $x = \{X_a\}$ be a permissible decomposition of $W$ (i.e.\ object of $\cD(W)$).
+We will define $\psi_{\cC;W}(x)$ to be a certain subset of $\prod_a \cC(X_a)$.
+Roughly speaking, $\psi_{\cC;W}(x)$ is the subset where the restriction maps from
+$\cC(X_a)$ and $\cC(X_b)$ agree whenever some part of $\bd X_a$ is glued to some part of $\bd X_b$.
+(Keep in mind that perhaps $a=b$.)
+Since we allow decompositions in which the intersection of $X_a$ and $X_b$ might be messy
+(see Example \ref{sin1x-example}), we must define $\psi_{\cC;W}(x)$ in a more roundabout way.
+
+Inductively, we may assume that we have already defined the colimit $\cl\cC(M)$ for $k{-}1$-manifolds $M$.
+(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 $\prod_a \cC(P_a)$.)
+
+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 $M_{i+1}$.
+We will define $\psi_{\cC;W}(x)$ be be the subset of $\prod_a \cC(X_a)$ which satisfies a series of conditions
+related to the gluings $M_{i-1} \to M_i$, $1\le i \le m$.
+By Axiom \ref{nca-boundary}, we have a map
+\[
+ \prod_a \cC(X_a) \to \cl\cC(\bd M_0) .
+\]
+The first condition is that the image of $\psi_{\cC;W}(x)$ in $\cl\cC(\bd M_0)$ is splittable
+along $\bd Y_0$ and $\bd Y'_0$, and that the restrictions to $\cl\cC(Y_0)$ and $\cl\cC(Y'_0)$ agree
+(with respect to the identification of $Y_0$ and $Y'_0$ provided by the gluing map).
+
+On the subset of $\prod_a \cC(X_a)$ which satisfies the first condition above, we have a restriction
+map to $\cl\cC(N_0)$ which we can compose with the gluing map
+$\cl\cC(N_0) \to \cl\cC(\bd M_1)$.
+The second condition is that the image of $\psi_{\cC;W}(x)$ in $\cl\cC(\bd M_1)$ is splittable
+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.
+
+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
+ball decompositions compatible with $x$.
+(If $x$ is a nice, non-pathological cell decomposition, then it is easy to see that gluing
+compatibility for one ball decomposition implies gluing compatibility for all other ball decompositions.
+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{...}
+
+\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.
@@ -1082,10 +1130,12 @@
\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 %%%%%%%%%%%%%%%%%%%%%%%
+
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 Equation \ref{eq:psi-C} as
+We can rewrite the colimit as
\begin{equation} \label{eq:psi-CC}
\psi_{\cC;W}(x) \deq \coprod_\beta \prod_a \cC(X_a; \beta) ,
\end{equation}