diff -r bc22926d4fb0 -r eb03c4a92f98 text/tqftreview.tex --- a/text/tqftreview.tex Thu Jun 03 09:47:18 2010 -0700 +++ b/text/tqftreview.tex Thu Jun 03 12:33:47 2010 -0700 @@ -5,7 +5,7 @@ \label{sec:tqftsviafields} In this section we review the notion of a ``system of fields and local relations". -For more details see \cite{kw:tqft}. From a system of fields and local relations we can readily construct TQFT invariants of manifolds. This is described in \S \ref{sec:constructing-a-TQFT}. A system of fields is very closely related to an $n$-category. In Example \ref{ex:traditional-n-categories(fields)}, which runs throughout this section, we sketch the construction of a system of fields from an $n$-category. We make this more precise for $n=1$ or $2$ in \S \ref{sec:example:traditional-n-categories(fields)}, and much later, after we've have given our own definition of a `topological $n$-category' in \S \ref{sec:ncats}, we explain precisely how to go back and forth between a topological $n$-category and a system of fields and local relations. +For more details see \cite{kw:tqft}. From a system of fields and local relations we can readily construct TQFT invariants of manifolds. This is described in \S \ref{sec:constructing-a-tqft}. A system of fields is very closely related to an $n$-category. In Example \ref{ex:traditional-n-categories(fields)}, which runs throughout this section, we sketch the construction of a system of fields from an $n$-category. We make this more precise for $n=1$ or $2$ in \S \ref{sec:example:traditional-n-categories(fields)}, and much later, after we've have given our own definition of a `topological $n$-category' in \S \ref{sec:ncats}, we explain precisely how to go back and forth between a topological $n$-category and a system of fields and local relations. We only consider compact manifolds, so if $Y \sub X$ is a closed codimension 0 submanifold of $X$, then $X \setmin Y$ implicitly means the closure @@ -21,7 +21,7 @@ oriented, topological, smooth, spin, etc. --- but for definiteness we will stick with unoriented PL.) -Fix a symmetric monoidal category $\cS$ whose objects are sets. While reading the definition, you should just think about the cases $\cS = \Set$ or $\cS = \Vect$. +Fix a symmetric monoidal category $\cS$. While reading the definition, you should just think about the cases $\cS = \Set$ or $\cS = \Vect$. The presentation here requires that the objects of $\cS$ have an underlying set, but this could probably be avoided if desired. A $n$-dimensional {\it system of fields} in $\cS$ is a collection of functors $\cC_k : \cM_k \to \Set$ for $0 \leq k \leq n$ @@ -326,13 +326,14 @@ %To harmonize notation with the next section, %let $\bc_0(X)$ be the vector space of finite linear combinations of fields on $X$, so %$\bc_0(X) = \lf(X)$. -Define $U(X) \sub \lf(X)$ to be the space of local relations in $\lf(X)$; -$U(X)$ is generated by things of the form $u\bullet r$, where -$u\in U(B)$ for some embedded $n$-ball $B\sub X$ and $r\in \cC(X\setmin B)$. -Define -\[ - A(X) \deq \lf(X) / U(X) . -\] +\begin{defn} +\label{defn:TQFT-invariant} +The TQFT invariant of $X$ associated to a system of fields $\cF$ and local relations $\cU$ is + $$A(X) \deq \lf(X) / U(X),$$ +where $\cU(X) \sub \lf(X)$ to be the space of local relations in $\lf(X)$; +$\cU(X)$ is generated by things of the form $u\bullet r$, where +$u\in \cU(B)$ for some embedded $n$-ball $B\sub X$ and $r\in \cC(X\setmin B)$. +\end{defn} (The blob complex, defined in the next section, is in some sense the derived version of $A(X)$.) If $X$ has boundary we can similarly define $A(X; c)$ for each