text/hochschild.tex
changeset 230 ebdcbb16f55e
parent 221 77b0cdeb0fcd
child 232 9a459c7f360e
equal deleted inserted replaced
229:9a9281dace31 230:ebdcbb16f55e
   190 a blob diagram could have multiple (nested) blobs whose
   190 a blob diagram could have multiple (nested) blobs whose
   191 boundaries contain *, on both the right and left of *.
   191 boundaries contain *, on both the right and left of *.
   192 
   192 
   193 We claim that $J_*$ is homotopy equivalent to $\bc_*(S^1)$.
   193 We claim that $J_*$ is homotopy equivalent to $\bc_*(S^1)$.
   194 Let $F_*^\ep \sub \bc_*(S^1)$ be the subcomplex where either
   194 Let $F_*^\ep \sub \bc_*(S^1)$ be the subcomplex where either
   195 (a) the point * is not the left boundary of any blob or
   195 (a) the point * is not on the boundary of any blob or
   196 (b) there are no labeled points to the right of * within distance $\ep$.
   196 (b) there are no labeled points or blob boundaries within distance $\ep$ of *.
   197 Note that all blob diagrams are in $F_*^\ep$ for $\ep$ sufficiently small.
   197 Note that all blob diagrams are in $F_*^\ep$ for $\ep$ sufficiently small.
   198 
   198 Let $b$ be a blob diagram in $F_*^\ep$.
   199 
   199 Define $f(b)$ to be the result of moving any blob boundary points which lie on *
   200 \nn{...}
   200 to distance $\ep$ from *.
   201 
   201 (Move right or left so as to shrink the blob.)
   202 
   202 Extend to get a chain map $f: F_*^\ep \to F_*^\ep$.
   203 
   203 By Lemma \ref{support-shrink}, $f$ is homotopic to the identity.
   204 We want to define a homotopy inverse $s: \bc_*(S^1) \to K_*(C)$ to the inclusion.
   204 Since the image of $f$ is in $J_*$, and since any blob chain is in $F_*^\ep$
       
   205 for $\ep$ sufficiently small, we have that $J_*$ is homotopic to all of $\bc_*(S^1)$.
       
   206 
       
   207 We now define a homotopy inverse $s: J_* \to K_*(C)$ to the inclusion $i$.
   205 If $y$ is a field defined on a neighborhood of *, define $s(y) = y$ if
   208 If $y$ is a field defined on a neighborhood of *, define $s(y) = y$ if
   206 * is a labeled point in $y$.
   209 * is a labeled point in $y$.
   207 Otherwise, define $s(y)$ to be the result of adding a label 1 (identity morphism) at *.
   210 Otherwise, define $s(y)$ to be the result of adding a label 1 (identity morphism) at *.
   208 Extending linearly, we get the desired map $s: \bc_*(S^1) \to K_*(C)$.
   211 Extending linearly, we get the desired map $s: \bc_*(S^1) \to K_*(C)$.
   209 It is easy to check that $s$ is a chain map and $s \circ i = \id$.
   212 It is easy to check that $s$ is a chain map and $s \circ i = \id$.
   213 spanned by blob diagrams
   216 spanned by blob diagrams
   214 where there are no labeled points
   217 where there are no labeled points
   215 in $N_\ep$, except perhaps $*$, and $N_\ep$ is either disjoint from or contained in 
   218 in $N_\ep$, except perhaps $*$, and $N_\ep$ is either disjoint from or contained in 
   216 every blob in the diagram.
   219 every blob in the diagram.
   217 Note that for any chain $x \in \bc_*(S^1)$, $x \in L_*^\ep$ for sufficiently small $\ep$.
   220 Note that for any chain $x \in \bc_*(S^1)$, $x \in L_*^\ep$ for sufficiently small $\ep$.
   218 \nn{what if * is on boundary of a blob?  need preliminary homotopy to prevent this.}
       
   219 
   221 
   220 We define a degree $1$ chain map $j_\ep: L_*^\ep \to L_*^\ep$ as follows. Let $x \in L_*^\ep$ be a blob diagram.
   222 We define a degree $1$ chain map $j_\ep: L_*^\ep \to L_*^\ep$ as follows. Let $x \in L_*^\ep$ be a blob diagram.
   221 \nn{maybe add figures illustrating $j_\ep$?}
   223 \nn{maybe add figures illustrating $j_\ep$?}
   222 If $*$ is not contained in any twig blob, we define $j_\ep(x)$ by adding $N_\ep$ as a new twig blob, with label $y - s(y)$ where $y$ is the restriction
   224 If $*$ is not contained in any twig blob, we define $j_\ep(x)$ by adding $N_\ep$ as a new twig blob, with label $y - s(y)$ where $y$ is the restriction
   223 of $x$ to $N_\ep$. If $*$ is contained in a twig blob $B$ with label $u=\sum z_i$,
   225 of $x$ to $N_\ep$. If $*$ is contained in a twig blob $B$ with label $u=\sum z_i$,