starting to revise the ancient TQFTs-from-fields section; other minor stuff
authorKevin Walker <kevin@canyon23.net>
Fri, 04 Jun 2010 08:15:08 -0700
changeset 339 9698f584e732
parent 338 adc0780aa5e7
child 340 f7da004e1f14
starting to revise the ancient TQFTs-from-fields section; other minor stuff
blob1.tex
text/ncat.tex
text/tqftreview.tex
--- a/blob1.tex	Thu Jun 03 23:08:47 2010 -0700
+++ b/blob1.tex	Fri Jun 04 08:15:08 2010 -0700
@@ -44,8 +44,13 @@
 \item[B] (S) look at this, decide what to keep
 
 \item Work in the references Chris Douglas gave us on the classification of local field theories, \cite{BDH-seminar,DSP-seminar,schommer-pries-thesis,0905.0465}.
-\item Make clear exactly what counts as a "blob diagram", and search for
-"blob diagram"
+\nn{KW: Do we need to do this?  We don't really classify field theories.
+I suppose our work could be interpreted as a alternative proof of cobordism hypothesis, but we 
+don't emphasize that at the moment.  
+On the other hand, I'm happy to do Chris a favor by citing this stuff.}
+
+\item Make clear exactly what counts as a ``blob diagram", and search for
+``blob diagram"
 
 \item Say something about stabilizing an $n$-category (centre), taking the top $k$ levels of a category, and the stabilization hypothesis?
 
--- a/text/ncat.tex	Thu Jun 03 23:08:47 2010 -0700
+++ b/text/ncat.tex	Fri Jun 04 08:15:08 2010 -0700
@@ -7,6 +7,7 @@
 \label{sec:ncats}
 
 \subsection{Definition of $n$-categories}
+\label{ss:n-cat-def}
 
 Before proceeding, we need more appropriate definitions of $n$-categories, 
 $A_\infty$ $n$-categories, modules for these, and tensor products of these modules.
@@ -536,7 +537,7 @@
 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}).
-For $X$ an $n$-ball and $c\in \cl{\cC}(\bd X)$, define $\cC(X)$ to finite linear
+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 $X$
 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 $D$,
--- a/text/tqftreview.tex	Thu Jun 03 23:08:47 2010 -0700
+++ b/text/tqftreview.tex	Fri Jun 04 08:15:08 2010 -0700
@@ -45,9 +45,11 @@
 \end{example}
 
 Now for the rest of the definition of system of fields.
+(Readers desiring a more precise definition should refer to Subsection \ref{ss:n-cat-def}
+and replace $k$-balls with $k$-manifolds.)
 \begin{enumerate}
 \item There are boundary restriction maps $\cC_k(X) \to \cC_{k-1}(\bd X)$, 
-and these maps are a natural
+and these maps comprise a natural
 transformation between the functors $\cC_k$ and $\cC_{k-1}\circ\bd$.
 For $c \in \cC_{k-1}(\bd X)$, we will denote by $\cC_k(X; c)$ the subset of 
 $\cC(X)$ which restricts to $c$.
@@ -55,13 +57,13 @@
 \item The subset $\cC_n(X;c)$ of top fields with a given boundary condition is an object in our symmetric monoidal category $\cS$. (This condition is of course trivial when $\cS = \Set$.) If the objects are sets with extra structure (e.g. $\cS = \Vect$ or $\Kom$), then this extra structure is considered part of the definition of $\cC_n$. Any maps mentioned below between top level fields must be morphisms in $\cS$.
 \item $\cC_k$ is compatible with the symmetric monoidal
 structures on $\cM_k$, $\Set$ and $\cS$: $\cC_k(X \du W) \cong \cC_k(X)\times \cC_k(W)$,
-compatibly with homeomorphisms, restriction to boundary, and orientation reversal.
+compatibly with homeomorphisms and restriction to boundary.
 We will call the projections $\cC(X_1 \du X_2) \to \cC(X_i)$
 restriction maps.
 \item Gluing without corners.
-Let $\bd X = Y \du -Y \du W$, where $Y$ and $W$ are closed $k{-}1$-manifolds.
-Let $X\sgl$ denote $X$ glued to itself along $\pm Y$.
-Using the boundary restriction, disjoint union, and (in one case) orientation reversal
+Let $\bd X = Y \du Y \du W$, where $Y$ and $W$ are closed $k{-}1$-manifolds.
+Let $X\sgl$ denote $X$ glued to itself along the two copies of $Y$.
+Using the boundary restriction and disjoint union
 maps, we get two maps $\cC_k(X) \to \cC(Y)$, corresponding to the two
 copies of $Y$ in $\bd X$.
 Let $\Eq_Y(\cC_k(X))$ denote the equalizer of these two maps.
@@ -70,15 +72,15 @@
 	\Eq_Y(\cC_k(X)) \hookrightarrow \cC_k(X\sgl) ,
 \]
 and this gluing map is compatible with all of the above structure (actions
-of homeomorphisms, boundary restrictions, orientation reversal, disjoint union).
+of homeomorphisms, boundary restrictions, disjoint union).
 Furthermore, up to homeomorphisms of $X\sgl$ isotopic to the identity,
 the gluing map is surjective.
-From the point of view of $X\sgl$ and the image $Y \subset X\sgl$ of the 
-gluing surface, we say that fields in the image of the gluing map
+We say that fields on $X\sgl$ in the image of the gluing map
 are transverse to $Y$ or splittable along $Y$.
 \item Gluing with corners.
-Let $\bd X = Y \cup -Y \cup W$, where $\pm Y$ and $W$ might intersect along their boundaries.
-Let $X\sgl$ denote $X$ glued to itself along $\pm Y$.
+Let $\bd X = Y \cup Y \cup W$, where the two copies of $Y$ and 
+$W$ might intersect along their boundaries.
+Let $X\sgl$ denote $X$ glued to itself along the two copies of $Y$.
 Note that $\bd X\sgl = W\sgl$, where $W\sgl$ denotes $W$ glued to itself
 (without corners) along two copies of $\bd Y$.
 Let $c\sgl \in \cC_{k-1}(W\sgl)$ be a be a splittable field on $W\sgl$ and let
@@ -97,8 +99,7 @@
 of homeomorphisms, boundary restrictions, orientation reversal, disjoint union).
 Furthermore, up to homeomorphisms of $X\sgl$ isotopic to the identity,
 the gluing map is surjective.
-From the point of view of $X\sgl$ and the image $Y \subset X\sgl$ of the 
-gluing surface, we say that fields in the image of the gluing map
+We say that fields in the image of the gluing map
 are transverse to $Y$ or splittable along $Y$.
 \item There are maps $\cC_{k-1}(Y) \to \cC_k(Y \times I)$, denoted
 $c \mapsto c\times I$.
@@ -137,8 +138,8 @@
 on $M$ generated by isotopy plus all instance of the above construction
 (for all appropriate $Y$ and $x$).
 
-\nn{should also say something about pseudo-isotopy}
-
+\nn{the following discussion of linearizing fields is kind of lame.
+maybe just assume things are already linearized.}
 
 \nn{remark that if top dimensional fields are not already linear
 then we will soon linearize them(?)}
@@ -188,7 +189,7 @@
 by $n$-category morphisms.
 
 Given an $n$-category $C$ with the right sort of duality
-(e.g. a pivotal 2-category, 1-category with duals, star 1-category, disklike $n$-category),
+(e.g. a pivotal 2-category, 1-category with duals, star 1-category),
 we can construct a system of fields as follows.
 Roughly speaking, $\cC(X)$ will the set of all embedded cell complexes in $X$
 with codimension $i$ cells labeled by $i$-morphisms of $C$.