text/ncat.tex
changeset 99 a3311a926113
parent 98 ec3af8dfcb3c
child 101 18611e566149
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98:ec3af8dfcb3c 99:a3311a926113
   251 we get a space version of an $A_\infty$ $n$-category, with $\Homeo_\bd(X)$ acting 
   251 we get a space version of an $A_\infty$ $n$-category, with $\Homeo_\bd(X)$ acting 
   252 instead of  $C_*(\Homeo_\bd(X))$.
   252 instead of  $C_*(\Homeo_\bd(X))$.
   253 Taking singular chains converts a space-type $A_\infty$ $n$-category into a chain complex
   253 Taking singular chains converts a space-type $A_\infty$ $n$-category into a chain complex
   254 type $A_\infty$ $n$-category.
   254 type $A_\infty$ $n$-category.
   255 
   255 
   256 
   256 \medskip
       
   257 
       
   258 The alert reader will have already noticed that our definition of (plain) $n$-category
       
   259 is extremely similar to our definition of topological fields.
       
   260 The only difference is that for the $n$-category definition we restrict our attention to balls
       
   261 (and their boundaries), while for fields we consider all manifolds.
       
   262 \nn{also: difference at the top dimension; fix this}
       
   263 Thus a system of fields determines an $n$-category simply by restricting our attention to
       
   264 balls.
       
   265 The $n$-category can be thought of as the local part of the fields.
       
   266 Conversely, given an $n$-category we can construct a system of fields via 
       
   267 \nn{gluing, or a universal construction}
       
   268 
       
   269 \nn{Next, say something about $A_\infty$ $n$-categories and ``homological" systems
       
   270 of fields.
       
   271 The universal (colimit) construction becomes our generalized definition of blob homology.
       
   272 Need to explain how it relates to the old definition.}
   257 
   273 
   258 \medskip
   274 \medskip
   259 
   275 
   260 \hrule
   276 \hrule
   261 
   277 
   273 \item blob complex is an example of an $A_\infty$ $n$-category
   289 \item blob complex is an example of an $A_\infty$ $n$-category
   274 \item fundamental $n$-groupoid is an example of an $A_\infty$ $n$-category
   290 \item fundamental $n$-groupoid is an example of an $A_\infty$ $n$-category
   275 \item traditional $n$-cat defs (e.g. *-1-cat, pivotal 2-cat) imply our def of plain $n$-cat
   291 \item traditional $n$-cat defs (e.g. *-1-cat, pivotal 2-cat) imply our def of plain $n$-cat
   276 \item conversely, our def implies other defs
   292 \item conversely, our def implies other defs
   277 \item traditional $A_\infty$ 1-cat def implies our def
   293 \item traditional $A_\infty$ 1-cat def implies our def
   278 \item ... and vice-versa
   294 \item ... and vice-versa (already done in appendix)
   279 \item say something about unoriented vs oriented vs spin vs pin for $n=1$ (and $n=2$?)
   295 \item say something about unoriented vs oriented vs spin vs pin for $n=1$ (and $n=2$?)
   280 \item spell out what difference (if any) Top vs PL vs Smooth makes
   296 \item spell out what difference (if any) Top vs PL vs Smooth makes
       
   297 \item explain relation between old-fashioned blob homology and new-fangled blob homology
   281 \end{itemize}
   298 \end{itemize}
   282 
   299 
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   300