diff -r c27e875508fd -r 90e0c5e7ae07 text/ncat.tex --- a/text/ncat.tex Fri Jun 04 20:43:14 2010 -0700 +++ b/text/ncat.tex Sat Jun 05 08:25:14 2010 -0700 @@ -621,24 +621,29 @@ \label{ex:traditional-n-categories} Given a `traditional $n$-category with strong duality' $C$ define $\cC(X)$, for $X$ a $k$-ball with $k < n$, -to be the set of all $C$-labeled sub cell complexes of $X$ (c.f. \S \ref{sec:fields}). +to be the set of all $C$-labeled embedded cell complexes of $X$ (c.f. \S \ref{sec:fields}). For $X$ an $n$-ball and $c\in \cl{\cC}(\bd X)$, define $\cC(X; c)$ to be finite linear -combinations of $C$-labeled sub cell complexes of $X$ +combinations of $C$-labeled embedded cell complexes of $X$ modulo the kernel of the evaluation map. Define a product morphism $a\times D$, for $D$ an $m$-ball, to be the product of the cell complex of $a$ with $D$, -with each cell labelled by the $m$-th iterated identity morphism of the corresponding cell for $a$. +with each cell labelled according to the corresponding cell for $a$. +(These two cells have the same codimension.) More generally, start with an $n{+}m$-category $C$ and a closed $m$-manifold $F$. Define $\cC(X)$, for $\dim(X) < n$, -to be the set of all $C$-labeled sub cell complexes of $X\times F$. +to be the set of all $C$-labeled embedded cell complexes of $X\times F$. Define $\cC(X; c)$, for $X$ an $n$-ball, to be the dual Hilbert space $A(X\times F; c)$. \nn{refer elsewhere for details?} - Recall we described a system of fields and local relations based on a `traditional $n$-category' $C$ in Example \ref{ex:traditional-n-categories(fields)} above. +\nn{KW: We already refer to \S \ref{sec:fields} above} Constructing a system of fields from $\cC$ recovers that example. \todo{Except that it doesn't: pasting diagrams v.s. string diagrams.} +\nn{KW: but the above example is all about string diagrams. the only difference is at the top level, +where the quotient is built in. +but (string diagrams)/(relations) is isomorphic to +(pasting diagrams composed of smaller string diagrams)/(relations)} \end{example} Finally, we describe a version of the bordism $n$-category suitable to our definitions. @@ -698,7 +703,9 @@ This example will be essential for Theorem \ref{product_thm} below, which allows us to compute the blob complex of a product. Notice that with $F$ a point, the above example is a construction turning a topological $n$-category $\cC$ into an $A_\infty$ $n$-category which we'll denote by $\bc_*(\cC)$. -We think of this as providing a `free resolution' of the topological $n$-category. +We think of this as providing a `free resolution' +\nn{`cofibrant replacement'?} +of the topological $n$-category. \todo{Say more here!} In fact, there is also a trivial, but mostly uninteresting, way to do this: we can think of each vector space associated to an $n$-ball as a chain complex concentrated in degree $0$, @@ -716,17 +723,37 @@ \end{example} + +Let $\cE\cB_n$ be the operad of smooth embeddings of $k$ (little) +copies of the standard $n$-ball $B^n$ into another (big) copy of $B^n$. +(We require that the interiors of the little balls be disjoint, but their +boundaries are allowed to meet. +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 $B^n$. +\nn{should we warn that the inclusion of this copy of $\Diff(B^n)$ is not 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 +in $B^n$.) +It is easy to see that $n$-fold loop spaces $\Omega^n(T)$ have the structure have +an action of $\cE\cB_n$. +\nn{add citation for this operad if we can find one} + \begin{example}[$E_n$ algebras] \rm \label{ex:e-n-alg} -Let $\cE\cB_n$ be the operad of smooth embeddings of $k$ (little) -copies of the standard $n$-ball $B^n$ into another (big) copy of $B^n$. -The operad $\cE\cB_n$ is homotopy equivalent to the standard framed little $n$-ball operad. -(By peeling the little balls, we see that both are homotopic to the space of $k$ framed points -in $B^n$.) Let $A$ be an $\cE\cB_n$-algebra. +Note that this implies a $\Diff(B^n)$ action on $A$, +since $\cE\cB_n$ contains a copy of $\Diff(B^n)$. We will define an $A_\infty$ $n$-category $\cC^A$. +If $X$ is a ball of dimension $k