diff -r 9e44c1469918 -r ec5c68b275c0 text/evmap.tex --- a/text/evmap.tex Mon Aug 23 21:19:55 2010 -0700 +++ b/text/evmap.tex Tue Aug 24 11:40:34 2010 -0700 @@ -124,8 +124,25 @@ \] Next we define $h_2$. - +Let $b\in C_2$ be a 2-blob diagram. +Let $B = |b|$, either a ball or a union of two balls. +By possibly working in a decomposition of $X$, we may assume that the ball(s) +of $B$ are disjointly embedded. +We will construct a 2-chain $s(b)\in \sbc_2$ such that +\[ + \bd(s(b)) = \bd(h_1(\bd b) + b) = s(\bd b) +\] +and the support of $s(b)$ is contained in $B$. +It then follows from \ref{disj-union-contract} that we can choose +$h_2(b) \in \bc_2(X)$ such that $\bd(h_2(b)) = s(b) - b - h_1(\bd b)$. +Similarly to the construction of $h_1$ above, +$s(b)$ consists of a series of 2-blob diagrams implementing a series +of small collar maps, plus a shrunken version of $b$. +The composition of all the collar maps shrinks $B$ to a sufficiently small +disjoint union of balls. + +Let $\cV_2$ be an auxiliary open cover of $X$, satisfying conditions specified below. \nn{...}