pnas/pnas.tex
changeset 622 dda6d3a00b09
parent 620 28b016b716b1
child 623 53aed9fdfcd9
child 633 2906548b2a95
equal deleted inserted replaced
621:e448415ad80a 622:dda6d3a00b09
   710 }
   710 }
   711 \end{equation*}
   711 \end{equation*}
   712 \end{thm}
   712 \end{thm}
   713 
   713 
   714 \begin{proof}(Sketch.)
   714 \begin{proof}(Sketch.)
   715 The most convenient way to prove this is to introduce yet another homotopy equivalent version of
   715 We introduce yet another homotopy equivalent version of
   716 the blob complex, $\cB\cT_*(X)$.
   716 the blob complex, $\cB\cT_*(X)$.
   717 Blob diagrams have a natural topology, which is ignored by $\bc_*(X)$.
   717 Blob diagrams have a natural topology, which is ignored by $\bc_*(X)$.
   718 In $\cB\cT_*(X)$ we take this topology into account, treating the blob diagrams as something
   718 In $\cB\cT_*(X)$ we take this topology into account, treating the blob diagrams as something
   719 analogous to a simplicial space (but with cone-product polyhedra replacing simplices).
   719 analogous to a simplicial space (but with cone-product polyhedra replacing simplices).
   720 More specifically, a generator of $\cB\cT_k(X)$ is an $i$-parameter family of $j$-blob diagrams, with $i+j=k$.
   720 More specifically, a generator of $\cB\cT_k(X)$ is an $i$-parameter family of $j$-blob diagrams, with $i+j=k$. An essential step in the proof of this equivalence is a result to the effect that a $k$-parameter family of homeomorphism can be localized to at most $k$ small sets.
   721 
   721 
   722 With this alternate version in hand, it is straightforward to prove the theorem.
   722 With this alternate version in hand, it is straightforward to prove the theorem.
   723 The evaluation map $\Homeo(X)\times BD_j(X)\to BD_j(X)$
   723 The evaluation map $\Homeo(X)\times BD_j(X)\to BD_j(X)$
   724 induces a chain map $\CH{X}\tensor C_*(BD_j(X))\to C_*(BD_j(X))$
   724 induces a chain map $\CH{X}\tensor C_*(BD_j(X))\to C_*(BD_j(X))$
   725 and hence a map $e_X: \CH{X} \tensor \cB\cT_*(X) \to \cB\cT_*(X)$.
   725 and hence a map $e_X: \CH{X} \tensor \cB\cT_*(X) \to \cB\cT_*(X)$.
   764 \begin{proof} (Sketch.)
   764 \begin{proof} (Sketch.)
   765 The $A_\infty$ action of $\bc_*(Y)$ follows from the naturality of the blob complex with respect to gluing
   765 The $A_\infty$ action of $\bc_*(Y)$ follows from the naturality of the blob complex with respect to gluing
   766 and the $C_*(\Homeo(-))$ action of Theorem \ref{thm:evaluation}.
   766 and the $C_*(\Homeo(-))$ action of Theorem \ref{thm:evaluation}.
   767 
   767 
   768 Let $T_*$ denote the self tensor product of $\bc_*(X)$, which is a homotopy colimit.
   768 Let $T_*$ denote the self tensor product of $\bc_*(X)$, which is a homotopy colimit.
   769 Let $X_{\mathrm gl}$ denote $X$ glued to itself along $Y$.
   769 There is a tautological map from the 0-simplices of $T_*$ to $\bc_*(X\bigcup_Y \selfarrow)$,
   770 There is a tautological map from the 0-simplices of $T_*$ to $\bc_*(X_{\mathrm gl})$,
       
   771 and this map can be extended to a chain map on all of $T_*$ by sending the higher simplices to zero.
   770 and this map can be extended to a chain map on all of $T_*$ by sending the higher simplices to zero.
   772 Constructing a homotopy inverse to this natural map invloves making various choices, but one can show that the
   771 Constructing a homotopy inverse to this natural map invloves making various choices, but one can show that the
   773 choices form contractible subcomplexes and apply the acyclic models theorem.
   772 choices form contractible subcomplexes and apply the acyclic models theorem.
   774 \end{proof}
   773 \end{proof}
   775 
   774