diff -r 6ebf92d2ccef -r 8f488e576afd text/ncat.tex --- a/text/ncat.tex Sat Jul 10 12:30:09 2010 -0600 +++ b/text/ncat.tex Sun Jul 11 14:31:56 2010 -0600 @@ -671,7 +671,7 @@ \begin{example}[Maps to a space] \rm \label{ex:maps-to-a-space}% -Let $T$be a topological space. +Let $T$ be a topological space. We define $\pi_{\leq n}(T)$, the fundamental $n$-category of $T$, as follows. For $X$ a $k$-ball with $k < n$, define $\pi_{\leq n}(T)(X)$ to be the set of all continuous maps from $X$ to $T$. @@ -713,8 +713,22 @@ Alternatively, we could equip the balls with fundamental classes.) \end{example} -The next example is only intended to be illustrative, as we don't specify which definition of a ``traditional $n$-category" we intend. -Further, most of these definitions don't even have an agreed-upon notion of ``strong duality", which we assume here. +\begin{example}[$n$-categories from TQFTs] +\rm +\label{ex:ncats-from-tqfts}% +Let $\cF$ be a TQFT in the sense of \S\ref{sec:fields}: an $n$-dimensional +system of fields (also denoted $\cF$) and local relations. +Let $W$ be an $n{-}j$-manifold. +Define the $j$-category $\cF(W)$ as follows. +If $X$ is a $k$-ball with $k