diff -r e2bab777d7c9 -r f4e13802a181 text/ncat.tex --- a/text/ncat.tex Thu May 13 12:07:02 2010 -0500 +++ b/text/ncat.tex Sat May 15 10:46:37 2010 -0500 @@ -34,11 +34,11 @@ For our definition, we will allow our $k$-morphisms to have any shape, so long as it is homeomorphic to the standard $k$-ball: -\begin{preliminary-axiom}{\ref{axiom:morphisms}}{Morphisms} +\begin{axiom}[Morphisms]{\textup{\textbf{[preliminary]}}} For any $k$-manifold $X$ homeomorphic to the standard $k$-ball, we have a set of $k$-morphisms $\cC_k(X)$. -\end{preliminary-axiom} +\end{axiom} By ``a $k$-ball" we mean any $k$-manifold which is homeomorphic to the standard $k$-ball. @@ -52,6 +52,7 @@ (This will imply ``strong duality", among other things.) So we replace the above with +\addtocounter{axiom}{-1} \begin{axiom}[Morphisms] \label{axiom:morphisms} For each $0 \le k \le n$, we have a functor $\cC_k$ from @@ -334,11 +335,11 @@ We start with the plain $n$-category case. -\begin{preliminary-axiom}{\ref{axiom:extended-isotopies}}{Isotopy invariance in dimension $n$} +\begin{axiom}[Isotopy invariance in dimension $n$]{\textup{\textbf{[preliminary]}}} Let $X$ be an $n$-ball and $f: X\to X$ be a homeomorphism which restricts to the identity on $\bd X$ and is isotopic (rel boundary) to the identity. Then $f$ acts trivially on $\cC(X)$; $f(a) = a$ for all $a\in \cC(X)$. -\end{preliminary-axiom} +\end{axiom} This axiom needs to be strengthened to force product morphisms to act as the identity. Let $X$ be an $n$-ball and $Y\sub\bd X$ be an $n{-}1$-ball. @@ -409,6 +410,7 @@ The revised axiom is +\addtocounter{axiom}{-1} \begin{axiom}{\textup{\textbf{[topological version]}} Extended isotopy invariance in dimension $n$} \label{axiom:extended-isotopies} Let $X$ be an $n$-ball and $f: X\to X$ be a homeomorphism which restricts @@ -721,8 +723,7 @@ permissible decomposition (filtration degree 0). Then we glue these together with mapping cylinders coming from gluing maps (filtration degree 1). -Then we kill the extra homology we just introduced with mapping cylinders between the mapping cylinders (filtration degree 2). -And so on. +Then we kill the extra homology we just introduced with mapping cylinders between the mapping cylinders (filtration degree 2), and so on. $\cC(W)$ is functorial with respect to homeomorphisms of $k$-manifolds. @@ -735,6 +736,19 @@ (actions of homeomorphisms); define $k$-cat $\cC(\cdot\times W)$} +Recall that Axiom \ref{} for an $n$-category provided functors $\cC$ from $k$-spheres to sets for $0 \leq k < n$. We claim now that these functors automatically agree with the colimits we have associated to spheres in this section. \todo{} \todo{In fact, we probably should do this for balls as well!} For the remainder of this section we will write $\underrightarrow{\cC}(W)$ for the colimit associated to an arbitary manifold $W$, to distinguish it, in the case that $W$ is a ball or a sphere, from $\cC(W)$, which is part of the definition of the $n$-category. After the next three lemmas, there will be no further need for this notational distinction. + +\begin{lem} +For a $k$-ball or $k$-sphere $W$, with $0\leq k < n$, $$\underrightarrow{\cC}(W) = \cC(W).$$ +\end{lem} + +\begin{lem} +For a topological $n$-category $\cC$, and an $n$-ball $B$, $$\underrightarrow{\cC}(B) = \cC(B).$$ +\end{lem} + +\begin{lem} +For an $A_\infty$ $n$-category $\cC$, and an $n$-ball $B$, $$\underrightarrow{\cC}(B) \quism \cC(B).$$ +\end{lem} \subsection{Modules}