text/evmap.tex
changeset 213 a60332c29d0b
parent 210 5200a0eac737
child 236 3feb6e24a518
equal deleted inserted replaced
212:c2d2a8f8d70c 213:a60332c29d0b
   111 %\nn{might need to restrict $S$; the proof uses partition of unity on $S$;
   111 %\nn{might need to restrict $S$; the proof uses partition of unity on $S$;
   112 %check this; or maybe just restrict the cover}
   112 %check this; or maybe just restrict the cover}
   113 Let $CM_*(S, T)$ denote the singular chains on the space of continuous maps
   113 Let $CM_*(S, T)$ denote the singular chains on the space of continuous maps
   114 from $S$ to $T$.
   114 from $S$ to $T$.
   115 Let $\cU$ be an open cover of $S$ which affords a partition of unity.
   115 Let $\cU$ be an open cover of $S$ which affords a partition of unity.
   116 \nn{for some $S$ and $\cU$ there is no partition of unity?  like if $S$ is not paracompact?}
   116 \nn{for some $S$ and $\cU$ there is no partition of unity?  like if $S$ is not paracompact?
       
   117 in any case, in our applications $S$ will always be a manifold}
   117 
   118 
   118 \begin{lemma}  \label{extension_lemma_b}
   119 \begin{lemma}  \label{extension_lemma_b}
   119 Let $x \in CM_k(S, T)$ be a singular chain such that $\bd x$ is adapted to $\cU$.
   120 Let $x \in CM_k(S, T)$ be a singular chain such that $\bd x$ is adapted to $\cU$.
   120 Then $x$ is homotopic (rel boundary) to some $x' \in CM_k(S, T)$ which is adapted to $\cU$.
   121 Then $x$ is homotopic (rel boundary) to some $x' \in CM_k(S, T)$ which is adapted to $\cU$.
   121 Furthermore, one can choose the homotopy so that its support is equal to the support of $x$.
   122 Furthermore, one can choose the homotopy so that its support is equal to the support of $x$.