text/evmap.tex
changeset 90 80fc6e03d586
parent 89 6c7662fcddc5
child 91 ea5d8fbcd5bc
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89:6c7662fcddc5 90:80fc6e03d586
   332 \begin{proof}
   332 \begin{proof}
   333 Let $c$ be a subset of the blobs of $b$.
   333 Let $c$ be a subset of the blobs of $b$.
   334 There exists $l > 0$ such that $\Nbd_u(c)$ is homeomorphic to $|c|$ for all $u < l$ 
   334 There exists $l > 0$ such that $\Nbd_u(c)$ is homeomorphic to $|c|$ for all $u < l$ 
   335 and all such $c$.
   335 and all such $c$.
   336 (Here we are using a piecewise smoothness assumption for $\bd c$, and also
   336 (Here we are using a piecewise smoothness assumption for $\bd c$, and also
   337 the fact that $\bd c$ is collared.)
   337 the fact that $\bd c$ is collared.
       
   338 We need to consider all such $c$ because all generators appearing in
       
   339 iterated boundaries of must be in $G_*^{i,m}$.)
   338 
   340 
   339 Let $r = \deg(b)$ and 
   341 Let $r = \deg(b)$ and 
   340 \[
   342 \[
   341 	t = r+n+m+1 .
   343 	t = r+n+m+1 = \deg(p\ot b) + m + 1.
   342 \]
   344 \]
   343 
   345 
   344 Choose $k = k_{bmn}$ such that
   346 Choose $k = k_{bmn}$ such that
   345 \[
   347 \[
   346 	t\ep_k < l
   348 	t\ep_k < l
   347 \]
   349 \]
   348 and
   350 and
   349 \[
   351 \[
   350 	n\cdot ( \phi_t \delta_i) < \ep_k/3 .
   352 	n\cdot (2 (\phi_t + 1) \delta_k) < \ep_k .
   351 \]
   353 \]
   352 Let $i \ge k_{bmn}$.
   354 Let $i \ge k_{bmn}$.
   353 Choose $j = j_i$ so that
   355 Choose $j = j_i$ so that
   354 \[
   356 \[
   355 	t\gamma_j < \ep_i/3
   357 	\gamma_j < \delta_i
   356 \]
   358 \]
   357 and also so that $\gamma_j$ is less than the constant $\eta(X, m, k)$ of Lemma \ref{xxyy5}.
   359 and also so that $\phi_t \gamma_j$ is less than the constant $\rho(M)$ of Lemma \ref{xxzz11}.
   358 
   360 
   359 \nn{...}
   361 Let $j \ge j_i$ and $p\in CD_n(X)$.
   360 
   362 Let $q$ be a generator appearing in $g_j(p)$.
       
   363 Note that $|q|$ is contained in a union of $n$ elements of the cover $\cU_j$,
       
   364 which implies that $|q|$ is contained in a union of $n$ metric balls of radius $\delta_i$.
       
   365 We must show that $q\ot b \in G_*^{i,m}$, which means finding neighborhoods
       
   366 $V_0,\ldots,V_m \sub X$ of $|q|\cup |b|$ such that each $V_j$
       
   367 is homeomorphic to a disjoint union of balls and
       
   368 \[
       
   369 	N_{i,n}(q\ot b) \subeq V_0 \subeq N_{i,n+1}(q\ot b)
       
   370 			\subeq V_1 \subeq \cdots \subeq V_m \subeq N_{i,t}(q\ot b) .
       
   371 \]
       
   372 By repeated applications of Lemma \ref{xx2phi} we can find neighborhoods $U_0,\ldots,U_m$
       
   373 of $|q|$, each homeomorphic to a disjoint union of balls, with
       
   374 \[
       
   375 	\Nbd_{\phi_{n+l} \delta_i}(|q|) \subeq U_l \subeq \Nbd_{\phi_{n+l+1} \delta_i}(|q|) .
       
   376 \]
       
   377 The inequalities above \nn{give ref} guarantee that we can find $u_l$ with 
       
   378 \[
       
   379 	(n+l)\ep_i \le u_l \le (n+l+1)\ep_i
       
   380 \]
       
   381 such that each component of $U_l$ is either disjoint from $\Nbd_{u_l}(|b|)$ or contained in 
       
   382 $\Nbd_{u_l}(|b|)$.
       
   383 This is because there are at most $n$ components of $U_l$, and each component
       
   384 has radius $\le (\phi_t + 1) \delta_i$.
       
   385 It follows that
       
   386 \[
       
   387 	V_l \deq \Nbd_{u_l}(|b|) \cup U_l
       
   388 \]
       
   389 is homeomorphic to a disjoint union of balls and satisfies
       
   390 \[
       
   391 	N_{i,n+l}(q\ot b) \subeq V_l \subeq N_{i,n+l+1}(q\ot b) .
       
   392 \]
       
   393 
       
   394 The same argument shows that each generator involved in iterated boundaries of $q\ot b$
       
   395 is in $G_*^{i,m}$.
   361 \end{proof}
   396 \end{proof}
   362 
   397 
   363 In the next few lemmas we have made no effort to optimize the various bounds.
   398 In the next few lemmas we have made no effort to optimize the various bounds.
   364 (The bounds are, however, optimal in the sense of minimizing the amount of work
   399 (The bounds are, however, optimal in the sense of minimizing the amount of work
   365 we do.  Equivalently, they are the first bounds we thought of.)
   400 we do.  Equivalently, they are the first bounds we thought of.)
   437 \]
   472 \]
   438 where $t = \phi_{k-1}(2\phi_{k-1}+2)r + \phi_{k-1} r$.
   473 where $t = \phi_{k-1}(2\phi_{k-1}+2)r + \phi_{k-1} r$.
   439 \end{proof}
   474 \end{proof}
   440 
   475 
   441 
   476 
   442 
       
   443 \medskip
   477 \medskip
   444 
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