diff -r fd5d1647f4f3 -r db18f7c32abe text/ncat.tex --- a/text/ncat.tex Sun May 09 22:32:37 2010 -0700 +++ b/text/ncat.tex Mon May 10 10:09:06 2010 -0700 @@ -1116,7 +1116,9 @@ (\cM_\cC\ot {_\cC\cN})^* \cong \hom_\cC(\cM_\cC \to (_\cC\cN)^*) . \] -We must now define the things appearing in the above equation. +In the next few paragraphs define the things appearing in the above equation: +$\cM_\cC\ot {_\cC\cN}$, $(\cM_\cC\ot {_\cC\cN})^*$, $(_\cC\cN)^*$ and finally +$\hom_\cC$. In the previous subsection we defined a tensor product of $A_\infty$ $n$-cat modules for general $n$. @@ -1135,12 +1137,52 @@ To each antirefinement we associate a chain map using the composition law of $\cC$ and the module actions of $\cC$ on $\cM$ and $\cN$. \def\olD{{\overline D}} +\def\cbar{{\bar c}} The underlying graded vector space of the homotopy colimit is \[ \bigoplus_l \bigoplus_{\olD} \psi(D_0)[l] , \] where $l$ runs through the natural numbers, $\olD = (D_0\to D_1\to\cdots\to D_l)$ runs through chains of antirefinements, and $[l]$ denotes a grading shift. +We will denote an element of the summand indexed by $\olD$ by +$\olD\ot m\ot\cbar\ot n$, where $m\ot\cbar\ot n \in \psi(D_0)$. +The boundary map is given (ignoring signs) by +\begin{eqnarray*} + \bd(\olD\ot m\ot\cbar\ot n) &=& \olD\ot\bd(m\ot\cbar)\ot n + \olD\ot m\ot\cbar\ot \bd n + \\ + & & \;\; (\bd_+ \olD)\ot m\ot\cbar\ot n + (\bd_0 \olD)\ot \rho(m\ot\cbar\ot n) , +\end{eqnarray*} +where $\bd_+ \olD = \sum_{i>0} (D_0, \cdots \widehat{D_i} \cdots , D_l)$ (the part of the simplicial +boundary which retains $D_0$), $\bd_0 \olD = (D_1, \cdots , D_l)$, +and $\rho$ is the gluing map associated to the antirefinement $D_0\to D_1$. + +$(\cM_\cC\ot {_\cC\cN})^*$ is just the dual chain complex to $\cM_\cC\ot {_\cC\cN}$: +\[ + \prod_l \prod_{\olD} (\psi(D_0)[l])^* , +\] +where $(\psi(D_0)[l])^*$ denotes the linear dual. +The boundary is given by +\begin{eqnarray*} + (\bd f)(\olD\ot m\ot\cbar\ot n) &=& f(\olD\ot\bd(m\ot\cbar)\ot n) + + f(\olD\ot m\ot\cbar\ot \bd n) + \\ + & & \;\; f((\bd_+ \olD)\ot m\ot\cbar\ot n) + f((\bd_0 \olD)\ot \rho(m\ot\cbar\ot n)) . +\end{eqnarray*} +(Again, we are ignoring signs.) + +Next we define the dual module $(_\cC\cN)^*$. +This will depend on a choice of interval $J$, just as the tensor product did. +Recall that $_\cC\cN$ is, among other things, a functor from right-marked intervals +to chain complexes. +Given $J$, we define for each $K\sub J$ which contains the {\it left} endpoint of $J$ +\[ + (_\cC\cN)^*(K) \deq ({_\cC\cN}(J\setmin K))^* , +\] +where $({_\cC\cN}(J\setmin K))^*$ denotes the (linear) dual of the chain complex associated +to the right-marked interval $J\setmin K$. +This extends to a functor from all left-marked intervals (not just those contained in $J$). +It's easy to verify the remaining module axioms. + +Now re reinterpret $(\cM_\cC\ot {_\cC\cN})^*$ +as some sort of morphism $\cM_\cC \to (_\cC\cN)^*$. \nn{...} @@ -1157,14 +1199,15 @@ In this subsection we define an $n{+}1$-category $\cS$ of ``sphere modules" whose objects correspond to $n$-categories. -This is a version of the familiar algebras-bimodules-intertwiners 2-category. +When $n=2$ +this is a version of the familiar algebras-bimodules-intertwiners 2-category. (Terminology: It is clearly appropriate to call an $S^0$ module a bimodule, but this is much less true for higher dimensional spheres, so we prefer the term ``sphere module" for the general case.) The $0$- through $n$-dimensional parts of $\cC$ are various sorts of modules, and we describe these first. -The $n{+}1$-dimensional part of $\cS$ consist of intertwiners +The $n{+}1$-dimensional part of $\cS$ consists of intertwiners (of garden-variety $1$-category modules associated to decorated $n$-balls). We will see below that in order for these $n{+}1$-morphisms to satisfy all of the duality requirements of an $n{+}1$-category, we will have to assume