string diagrams have stratifications more general than mere cell complexes
authorKevin Walker <kevin@canyon23.net>
Sat, 07 May 2011 09:40:20 -0700
changeset 772 73fc4868c039
parent 771 249ccaa26fee
child 773 775b5ca42bed
string diagrams have stratifications more general than mere cell complexes
blob to-do
blob_changes_v3
text/tqftreview.tex
--- a/blob to-do	Sat May 07 09:27:21 2011 -0700
+++ b/blob to-do	Sat May 07 09:40:20 2011 -0700
@@ -62,5 +62,3 @@
 
 * SCOTT: make sure acknowledge list doesn't omit anyone from blob seminar (I think I have all the speakers)
 
-* fix "cell decomposition" (\nn remark) in string-diagram-fields def
-
--- a/blob_changes_v3	Sat May 07 09:27:21 2011 -0700
+++ b/blob_changes_v3	Sat May 07 09:40:20 2011 -0700
@@ -17,5 +17,6 @@
 - fixed statement of compatibility of product morphisms with gluing
 - added remark about manifolds which do not admit ball decompositions; restricted product theorem (7.1.1) to apply only to these manifolds
 - added remarks about categories of defects
+- clarified that the "cell complexes" in string diagrams are actually a bit more general
 - 
 
--- a/text/tqftreview.tex	Sat May 07 09:27:21 2011 -0700
+++ b/text/tqftreview.tex	Sat May 07 09:40:20 2011 -0700
@@ -277,10 +277,6 @@
 
 We will always assume that our $n$-categories have linear $n$-morphisms.
 
-\nn{need to replace ``cell decomposition" below with something looser.  not sure what to call it.
-maybe ``nice stratification"??  the link of each piece of each stratum should be a cell decomposition of
-a sphere, but that's probably all we need.  or maybe refineable to a cell decomp?}
-
 For $n=1$, a field on a 0-manifold $P$ is a labeling of each point of $P$ with
 an object (0-morphism) of the 1-category $C$.
 A field on a 1-manifold $S$ consists of
@@ -356,6 +352,13 @@
 \end{itemize}
 
 
+It is customary when drawing string diagrams to omit identity morphisms.
+In the above context, this corresponds to erasing cells which are labeled by identity morphisms.
+The resulting structure might not, strictly speaking, be a cell complex.
+So when we write ``cell complex" above we really mean a stratification which can be
+refined to a genuine cell complex.
+
+
 
 \subsection{Local relations}
 \label{sec:local-relations}