text/hochschild.tex
changeset 252 d6466180cd66
parent 244 cf01e213044a
child 257 ae5a542c958e
equal deleted inserted replaced
251:195b767cafdb 252:d6466180cd66
   308             & = \sum_j d_{j,1} \cdots d_{j,k_j} m_j d_{j,1}' \cdots d_{j,k'_j}' c_1 \cdots c_k \\
   308             & = \sum_j d_{j,1} \cdots d_{j,k_j} m_j d_{j,1}' \cdots d_{j,k'_j}' c_1 \cdots c_k \\
   309             & = 0
   309             & = 0
   310 \end{align*}
   310 \end{align*}
   311 where this time we use the fact that we're mapping to $\coinv{M}$, not just $M$.
   311 where this time we use the fact that we're mapping to $\coinv{M}$, not just $M$.
   312 
   312 
   313 The map $\pi \compose \ev: H_0(K_*(M)) \to \coinv{M}$ is clearly surjective ($\ev$ surjects onto $M$); we now show that it's injective. \todo{}
   313 The map $\pi \compose \ev: H_0(K_*(M)) \to \coinv{M}$ is clearly surjective ($\ev$ surjects onto $M$); we now show that it's injective.
       
   314 This is equivalent to showing that 
       
   315 \[
       
   316 	\ev\inv(\ker(\pi)) \sub \bd K_1(M) .
       
   317 \]
       
   318 The above inclusion follows from
       
   319 \[
       
   320 	\ker(\ev) \sub \bd K_1(M)
       
   321 \]
       
   322 and
       
   323 \[
       
   324 	\ker(\pi) \sub \ev(\bd K_1(M)) .
       
   325 \]
       
   326 Let $x = \sum x_i$ be in the kernel of $\ev$, where each $x_i$ is a configuration of 
       
   327 labeled points in $S^1$.
       
   328 Since the sum is finite, we can find an interval (blob) $B$ in $S^1$
       
   329 such that for each $i$ the $C$-labeled points of $x_i$ all lie to the right of the 
       
   330 base point *.
       
   331 Let $y_i$ be the restriction of $x_i$ to $B$ and $y = \sum y_i$.
       
   332 Let $r$ be the ``empty" field on $S^1 \setmin B$.
       
   333 It follows that $y \in U(B)$ and 
       
   334 \[
       
   335 	\bd(B, y, r) = x .
       
   336 \]
       
   337 $\ker(\pi)$ is generated by elements of the form $cm - mc$.
       
   338 As shown in Figure \ref{fig:hochschild-1-chains}, $cm - mc$ lies in $\ev(\bd K_1(M))$.
   314 \end{proof}
   339 \end{proof}
       
   340 
   315 \begin{proof}[Proof of Lemma \ref{lem:hochschild-free}]
   341 \begin{proof}[Proof of Lemma \ref{lem:hochschild-free}]
   316 We show that $K_*(C\otimes C)$ is
   342 We show that $K_*(C\otimes C)$ is
   317 quasi-isomorphic to the 0-step complex $C$. We'll do this in steps, establishing quasi-isomorphisms and homotopy equivalences
   343 quasi-isomorphic to the 0-step complex $C$. We'll do this in steps, establishing quasi-isomorphisms and homotopy equivalences
   318 $$K_*(C \tensor C) \quismto K'_* \htpyto K''_* \quismto C.$$
   344 $$K_*(C \tensor C) \quismto K'_* \htpyto K''_* \quismto C.$$
   319 
   345 
   332 (See Figure \ref{fig:sy}.) Note that $y - s_\ep(y) \in U(N_\ep)$. 
   358 (See Figure \ref{fig:sy}.) Note that $y - s_\ep(y) \in U(N_\ep)$. 
   333 Let $\sigma_\ep: K_*^\ep \to K_*^\ep$ be the chain map
   359 Let $\sigma_\ep: K_*^\ep \to K_*^\ep$ be the chain map
   334 given by replacing the restriction $y$ to $N_\ep$ of each field
   360 given by replacing the restriction $y$ to $N_\ep$ of each field
   335 appearing in an element of  $K_*^\ep$ with $s_\ep(y)$.
   361 appearing in an element of  $K_*^\ep$ with $s_\ep(y)$.
   336 Note that $\sigma_\ep(x) \in K'_*$.
   362 Note that $\sigma_\ep(x) \in K'_*$.
   337 \begin{figure}[!ht]
   363 \begin{figure}[t]
   338 \begin{align*}
   364 \begin{align*}
   339 y & = \mathfig{0.2}{hochschild/y} &
   365 y & = \mathfig{0.2}{hochschild/y} &
   340 s_\ep(y) & = \mathfig{0.2}{hochschild/sy}
   366 s_\ep(y) & = \mathfig{0.2}{hochschild/sy}
   341 \end{align*}
   367 \end{align*}
   342 \caption{Defining $s_\ep$.}
   368 \caption{Defining $s_\ep$.}
   411 Define $h_1(x) = y$.
   437 Define $h_1(x) = y$.
   412 The general case is similar, except that we have to take lower order homotopies into account.
   438 The general case is similar, except that we have to take lower order homotopies into account.
   413 Let $x \in K'_k$.
   439 Let $x \in K'_k$.
   414 If $*$ is not contained in any of the blobs of $x$, then define $h_k(x) = 0$.
   440 If $*$ is not contained in any of the blobs of $x$, then define $h_k(x) = 0$.
   415 Otherwise, let $B$ be the outermost blob of $x$ containing $*$.
   441 Otherwise, let $B$ be the outermost blob of $x$ containing $*$.
   416 By xxxx above, $x = x' \bullet p$, where $x'$ is supported on $B$ and $p$ is supported away from $B$.
   442 We can decompose $x = x' \bullet p$, 
       
   443 where $x'$ is supported on $B$ and $p$ is supported away from $B$.
   417 So $x' \in G'_l$ for some $l \le k$.
   444 So $x' \in G'_l$ for some $l \le k$.
   418 Choose $x'' \in G''_l$ such that $\bd x'' = \bd (x' - h_{l-1}\bd x')$.
   445 Choose $x'' \in G''_l$ such that $\bd x'' = \bd (x' - h_{l-1}\bd x')$.
   419 Choose $y \in G'_{l+1}$ such that $\bd y = x' - x'' - h_{l-1}\bd x'$.
   446 Choose $y \in G'_{l+1}$ such that $\bd y = x' - x'' - h_{l-1}\bd x'$.
   420 Define $h_k(x) = y \bullet p$.
   447 Define $h_k(x) = y \bullet p$.
   421 This completes the proof that $i: K''_* \to K'_*$ is a homotopy equivalence.
   448 This completes the proof that $i: K''_* \to K'_*$ is a homotopy equivalence.
   454 In degree 0, we send $m\in M$ to the 0-blob diagram $\mathfig{0.05}{hochschild/0-chains}$; the base point
   481 In degree 0, we send $m\in M$ to the 0-blob diagram $\mathfig{0.05}{hochschild/0-chains}$; the base point
   455 in $S^1$ is labeled by $m$ and there are no other labeled points.
   482 in $S^1$ is labeled by $m$ and there are no other labeled points.
   456 In degree 1, we send $m\ot a$ to the sum of two 1-blob diagrams
   483 In degree 1, we send $m\ot a$ to the sum of two 1-blob diagrams
   457 as shown in Figure \ref{fig:hochschild-1-chains}.
   484 as shown in Figure \ref{fig:hochschild-1-chains}.
   458 
   485 
   459 \begin{figure}[!ht]
   486 \begin{figure}[t]
   460 \begin{equation*}
   487 \begin{equation*}
   461 \mathfig{0.4}{hochschild/1-chains}
   488 \mathfig{0.4}{hochschild/1-chains}
   462 \end{equation*}
   489 \end{equation*}
   463 \begin{align*}
   490 \begin{align*}
   464 u_1 & = \mathfig{0.05}{hochschild/u_1-1} - \mathfig{0.05}{hochschild/u_1-2} & u_2 & = \mathfig{0.05}{hochschild/u_2-1} - \mathfig{0.05}{hochschild/u_2-2} 
   491 u_1 & = \mathfig{0.05}{hochschild/u_1-1} - \mathfig{0.05}{hochschild/u_1-2} & u_2 & = \mathfig{0.05}{hochschild/u_2-1} - \mathfig{0.05}{hochschild/u_2-2} 
   465 \end{align*}
   492 \end{align*}
   466 \caption{The image of $m \tensor a$ in the blob complex.}
   493 \caption{The image of $m \tensor a$ in the blob complex.}
   467 \label{fig:hochschild-1-chains}
   494 \label{fig:hochschild-1-chains}
   468 \end{figure}
   495 \end{figure}
   469 
   496 
   470 \begin{figure}[!ht]
   497 \begin{figure}[t]
   471 \begin{equation*}
   498 \begin{equation*}
   472 \mathfig{0.6}{hochschild/2-chains-0}
   499 \mathfig{0.6}{hochschild/2-chains-0}
   473 \end{equation*}
   500 \end{equation*}
   474 \begin{equation*}
   501 \begin{equation*}
   475 \mathfig{0.4}{hochschild/2-chains-1} \qquad \mathfig{0.4}{hochschild/2-chains-2}
   502 \mathfig{0.4}{hochschild/2-chains-1} \qquad \mathfig{0.4}{hochschild/2-chains-2}
   476 \end{equation*}
   503 \end{equation*}
   477 \caption{The 0-, 1- and 2-chains in the image of $m \tensor a \tensor b$. Only the supports of the 1- and 2-blobs are shown.}
   504 \caption{The 0-, 1- and 2-chains in the image of $m \tensor a \tensor b$. Only the supports of the 1- and 2-blobs are shown.}
   478 \label{fig:hochschild-2-chains}
   505 \label{fig:hochschild-2-chains}
   479 \end{figure}
   506 \end{figure}
   480 
   507 
   481 \begin{figure}[!ht]
   508 \begin{figure}[t]
   482 \begin{equation*}
   509 \begin{equation*}
   483 A = \mathfig{0.1}{hochschild/v_1} + \mathfig{0.1}{hochschild/v_2} + \mathfig{0.1}{hochschild/v_3} + \mathfig{0.1}{hochschild/v_4}
   510 A = \mathfig{0.1}{hochschild/v_1} + \mathfig{0.1}{hochschild/v_2} + \mathfig{0.1}{hochschild/v_3} + \mathfig{0.1}{hochschild/v_4}
   484 \end{equation*}
   511 \end{equation*}
   485 \begin{align*}
   512 \begin{align*}
   486 v_1 & = \mathfig{0.05}{hochschild/v_1-1} -  \mathfig{0.05}{hochschild/v_1-2} &  v_2 & = \mathfig{0.05}{hochschild/v_2-1} -  \mathfig{0.05}{hochschild/v_2-2} \\ 
   513 v_1 & = \mathfig{0.05}{hochschild/v_1-1} -  \mathfig{0.05}{hochschild/v_1-2} &  v_2 & = \mathfig{0.05}{hochschild/v_2-1} -  \mathfig{0.05}{hochschild/v_2-2} \\