text/hochschild.tex
changeset 551 9dfb5db2acd7
parent 512 050dba5e7bdd
child 558 c393d1202724
equal deleted inserted replaced
550:c9f41c18a96f 551:9dfb5db2acd7
   453 First, a lemma:  Let $G''_*$ and $G'_*$ be defined similarly to $K''_*$ and $K'_*$, except with
   453 First, a lemma:  Let $G''_*$ and $G'_*$ be defined similarly to $K''_*$ and $K'_*$, except with
   454 $S^1$ replaced by some neighborhood $N$ of $* \in S^1$.
   454 $S^1$ replaced by some neighborhood $N$ of $* \in S^1$.
   455 ($G''_*$ and $G'_*$ depend on $N$, but that is not reflected in the notation.)
   455 ($G''_*$ and $G'_*$ depend on $N$, but that is not reflected in the notation.)
   456 Then $G''_*$ and $G'_*$ are both contractible
   456 Then $G''_*$ and $G'_*$ are both contractible
   457 and the inclusion $G''_* \sub G'_*$ is a homotopy equivalence.
   457 and the inclusion $G''_* \sub G'_*$ is a homotopy equivalence.
   458 For $G'_*$ the proof is the same as in (\ref{bcontract}), except that the splitting
   458 For $G'_*$ the proof is the same as in Lemma \ref{bcontract}, except that the splitting
   459 $G'_0 \to H_0(G'_*)$ concentrates the point labels at two points to the right and left of $*$.
   459 $G'_0 \to H_0(G'_*)$ concentrates the point labels at two points to the right and left of $*$.
   460 For $G''_*$ we note that any cycle is supported away from $*$.
   460 For $G''_*$ we note that any cycle is supported away from $*$.
   461 Thus any cycle lies in the image of the normal blob complex of a disjoint union
   461 Thus any cycle lies in the image of the normal blob complex of a disjoint union
   462 of two intervals, which is contractible by (\ref{bcontract}) and (\ref{disj-union-contract}).
   462 of two intervals, which is contractible by Lemma \ref{bcontract} and Corollary \ref{disj-union-contract}.
   463 Finally, it is easy to see that the inclusion
   463 Finally, it is easy to see that the inclusion
   464 $G''_* \to G'_*$ induces an isomorphism on $H_0$.
   464 $G''_* \to G'_*$ induces an isomorphism on $H_0$.
   465 
   465 
   466 Next we construct a degree 1 map (homotopy) $h: K'_* \to K'_*$ such that
   466 Next we construct a degree 1 map (homotopy) $h: K'_* \to K'_*$ such that
   467 for all $x \in K'_*$ we have
   467 for all $x \in K'_*$ we have