text/ncat.tex
changeset 826 979c947d0b82
parent 822 9e695fc9b13c
child 833 f40f726d6cca
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  1518 
  1518 
  1519 \medskip
  1519 \medskip
  1520 
  1520 
  1521 $\cl{\cC}(W)$ is functorial with respect to homeomorphisms of $k$-manifolds. 
  1521 $\cl{\cC}(W)$ is functorial with respect to homeomorphisms of $k$-manifolds. 
  1522 Restricting the $k$-spheres, we have now proved Lemma \ref{lem:spheres}.
  1522 Restricting the $k$-spheres, we have now proved Lemma \ref{lem:spheres}.
  1523 
       
  1524 It is easy to see that
       
  1525 there are well-defined maps $\cl{\cC}(W)\to\cl{\cC}(\bd W)$, and that these maps
       
  1526 comprise a natural transformation of functors.
       
  1527 
       
  1528 
       
  1529 
  1523 
  1530 \begin{lem}
  1524 \begin{lem}
  1531 \label{lem:colim-injective}
  1525 \label{lem:colim-injective}
  1532 Let $W$ be a manifold of dimension less than $n$.  Then for each
  1526 Let $W$ be a manifold of dimension less than $n$.  Then for each
  1533 decomposition $x$ of $W$ the natural map $\psi_{\cC;W}(x)\to \cl{\cC}(W)$ is injective.
  1527 decomposition $x$ of $W$ the natural map $\psi_{\cC;W}(x)\to \cl{\cC}(W)$ is injective.