text/ncat.tex
changeset 725 e27bc92e5d9b
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   202 \caption{Combining two balls to get a full boundary.}\label{blah3}\end{figure}
   202 \caption{Combining two balls to get a full boundary.}\label{blah3}\end{figure}
   203 
   203 
   204 Note that we insist on injectivity above. 
   204 Note that we insist on injectivity above. 
   205 The lemma follows from Definition \ref{def:colim-fields} and Lemma \ref{lem:colim-injective}.
   205 The lemma follows from Definition \ref{def:colim-fields} and Lemma \ref{lem:colim-injective}.
   206 %\nn{we might want a more official looking proof...}
   206 %\nn{we might want a more official looking proof...}
       
   207 
       
   208 We do not insist on surjectivity of the gluing map, since this is not satisfied by all of the examples
       
   209 we are trying to axiomatize.
       
   210 If our $k$-morphisms $\cC(X)$ are labeled cell complexes embedded in $X$, then a $k$-morphism is
       
   211 in the image of the gluing map precisely which the cell complex is in general position
       
   212 with respect to $E$.
   207 
   213 
   208 If $S$ is a 0-sphere (the case $k=1$ above), then $S$ can be identified with the {\it disjoint} union
   214 If $S$ is a 0-sphere (the case $k=1$ above), then $S$ can be identified with the {\it disjoint} union
   209 of two 0-balls $B_1$ and $B_2$ and the colimit construction $\cl{\cC}(S)$ can be identified
   215 of two 0-balls $B_1$ and $B_2$ and the colimit construction $\cl{\cC}(S)$ can be identified
   210 with the (ordinary, not fibered) product $\cC(B_1) \times \cC(B_2)$.
   216 with the (ordinary, not fibered) product $\cC(B_1) \times \cC(B_2)$.
   211 
   217