text/comm_alg.tex
changeset 236 3feb6e24a518
parent 166 75f5c197a0d4
child 266 e2bab777d7c9
equal deleted inserted replaced
233:0488412c274b 236:3feb6e24a518
    93 \nn{still to do: show indep of choice of metric; show compositions are homotopic to the identity
    93 \nn{still to do: show indep of choice of metric; show compositions are homotopic to the identity
    94 (for this, might need a lemma that says we can assume that blob diameters are small)}
    94 (for this, might need a lemma that says we can assume that blob diameters are small)}
    95 \end{proof}
    95 \end{proof}
    96 
    96 
    97 
    97 
    98 \begin{prop} \label{ktcdprop}
    98 \begin{prop} \label{ktchprop}
    99 The above maps are compatible with the evaluation map actions of $C_*(\Diff(M))$.
    99 The above maps are compatible with the evaluation map actions of $C_*(\Diff(M))$.
   100 \end{prop}
   100 \end{prop}
   101 
   101 
   102 \begin{proof}
   102 \begin{proof}
   103 The actions agree in degree 0, and both are compatible with gluing.
   103 The actions agree in degree 0, and both are compatible with gluing.
   104 (cf. uniqueness statement in \ref{CDprop}.)
   104 (cf. uniqueness statement in \ref{CHprop}.)
   105 \end{proof}
   105 \end{proof}
   106 
   106 
   107 \medskip
   107 \medskip
   108 
   108 
   109 In view of \ref{hochthm}, we have proved that $HH_*(k[t]) \cong C_*(\Sigma^\infty(S^1), k)$,
   109 In view of \ref{hochthm}, we have proved that $HH_*(k[t]) \cong C_*(\Sigma^\infty(S^1), k)$,
   126 of course $\Sigma^0(S^1)$ is a point.
   126 of course $\Sigma^0(S^1)$ is a point.
   127 Thus the singular homology $H_i(\Sigma^\infty(S^1))$ has infinitely many generators for $i=0,1$
   127 Thus the singular homology $H_i(\Sigma^\infty(S^1))$ has infinitely many generators for $i=0,1$
   128 and is zero for $i\ge 2$.
   128 and is zero for $i\ge 2$.
   129 \nn{say something about $t$-degrees also matching up?}
   129 \nn{say something about $t$-degrees also matching up?}
   130 
   130 
   131 By xxxx and \ref{ktcdprop}, 
   131 By xxxx and \ref{ktchprop}, 
   132 the cyclic homology of $k[t]$ is the $S^1$-equivariant homology of $\Sigma^\infty(S^1)$.
   132 the cyclic homology of $k[t]$ is the $S^1$-equivariant homology of $\Sigma^\infty(S^1)$.
   133 Up to homotopy, $S^1$ acts by $j$-fold rotation on $\Sigma^j(S^1) \simeq S^1/j$.
   133 Up to homotopy, $S^1$ acts by $j$-fold rotation on $\Sigma^j(S^1) \simeq S^1/j$.
   134 If $k = \z$, $\Sigma^j(S^1)$ contributes the homology of an infinite lens space: $\z$ in degree
   134 If $k = \z$, $\Sigma^j(S^1)$ contributes the homology of an infinite lens space: $\z$ in degree
   135 0, $\z/j \z$ in odd degrees, and 0 in positive even degrees.
   135 0, $\z/j \z$ in odd degrees, and 0 in positive even degrees.
   136 The point $\Sigma^0(S^1)$ contributes the homology of $BS^1$ which is $\z$ in even 
   136 The point $\Sigma^0(S^1)$ contributes the homology of $BS^1$ which is $\z$ in even