talks/20100625-StonyBrook/categorification.tex
changeset 379 6caac26b5c29
parent 378 e5867a64cae5
child 380 6876295aec26
equal deleted inserted replaced
378:e5867a64cae5 379:6caac26b5c29
    10 
    10 
    11 %\setbeameroption{previous slide on second screen=right}
    11 %\setbeameroption{previous slide on second screen=right}
    12 
    12 
    13 \author[Scott Morrison]{Scott Morrison \\ \texttt{http://tqft.net/} \\ joint work with Kevin Walker}
    13 \author[Scott Morrison]{Scott Morrison \\ \texttt{http://tqft.net/} \\ joint work with Kevin Walker}
    14 \institute{UC Berkeley / Miller Institute for Basic Research}
    14 \institute{UC Berkeley / Miller Institute for Basic Research}
    15 \title{Blob homology, part $\mathbb{I}$}
    15 \title{The blob complex}
    16 \date{Homotopy Theory and Higher Algebraic Structures, UC Riverside, November 10 2009 \\ \begin{description}\item[slides, part $\mathbb{I}$:]\url{http://tqft.net/UCR-blobs1} \item[slides, part $\mathbb{II}$:]\url{http://tqft.net/UCR-blobs2} \item[draft:]\url{http://tqft.net/blobs}\end{description}}
    16 \date{Low-Dimensional Topology and Categorification, \\Stony Brook University, June 21-25 2010 \\ \begin{description}\item[slides:]\url{http://tqft.net/sunysb-blobs} \item[paper:]\url{http://tqft.net/blobs}\end{description}}
    17 
    17 
    18 \begin{document}
    18 \begin{document}
    19 
    19 
    20 \frame{\titlepage}
    20 \frame{\titlepage}
    21 
    21 
    22 \beamertemplatetransparentcovered 
    22 \beamertemplatetransparentcovered 
       
    23 
       
    24 \setbeamertemplate{navigation symbols}{}  % no navigation symbols, please
       
    25 
    23 
    26 
    24 \mode<beamer>{\setbeamercolor{block title}{bg=green!40!black}}
    27 \mode<beamer>{\setbeamercolor{block title}{bg=green!40!black}}
    25 
    28 
    26 \beamersetuncovermixins 
    29 \beamersetuncovermixins 
    27 {\opaqueness<1->{60}} 
    30 {\opaqueness<1->{60}} 
    30 
    33 
    31 
    34 
    32 \section{Overview}
    35 \section{Overview}
    33 
    36 
    34    \begin{frame}<beamer>
    37    \begin{frame}<beamer>
    35        \frametitle{Blob homology}
    38        \frametitle{The blob complex}
    36        \begin{quote}
    39        \begin{quote}
    37       ... homotopical topology and TQFT have grown so close that I have started thinking that they are turning into the language of new foundations. 
    40       ... homotopical topology and TQFT have grown so close that I have started thinking that they are turning into the language of new foundations. 
    38         \end{quote}
    41         \end{quote}
    39         \flushright{--- \href{http://www.ams.org/notices/200910/rtx091001268p.pdf}{Yuri Manin, September 2008}}
    42         \flushright{--- \href{http://www.ams.org/notices/200910/rtx091001268p.pdf}{Yuri Manin, September 2008}}
    40       \tableofcontents
    43       \tableofcontents
    41 \end{frame}
    44 \end{frame}
    42 
    45 
    43 \begin{frame}{What is \emph{blob homology}?}
    46 \begin{frame}{What is \emph{the blob complex}?}
    44 \begin{block}{}
    47 \begin{block}{}
    45 The blob complex takes an $n$-manifold $\cM$ and an `$n$-category with strong duality' $\cC$ and produces a chain complex, $\bc_*(\cM; \cC)$.
    48 The blob complex takes an $n$-manifold $\cM$ and an `$n$-category with strong duality' $\cC$ and produces a chain complex, $\bc_*(\cM; \cC)$.
    46 \end{block}
    49 \end{block}
    47 \tikzstyle{description}=[gray, font=\tiny, text centered, text width=2cm]
    50 \tikzstyle{description}=[gray, font=\tiny, text centered, text width=2cm]
    48 \begin{tikzpicture}[]
    51 \begin{tikzpicture}[]
    51 % still covered={\opaqueness<1>{15}\opaqueness<2>{10}\opaqueness<3>{5}\opaqueness<4->{2}},
    54 % still covered={\opaqueness<1>{15}\opaqueness<2>{10}\opaqueness<3>{5}\opaqueness<4->{2}},
    52  again covered={\opaqueness<1->{50}}
    55  again covered={\opaqueness<1->{50}}
    53 }
    56 }
    54 
    57 
    55 \node[red] (blobs) at (0,0) {$H(\bc_*(\cM; \cC))$};
    58 \node[red] (blobs) at (0,0) {$H(\bc_*(\cM; \cC))$};
    56 \uncover<1>{
    59 \uncover<2>{
    57 \node[blue] (skein) at (4,0) {$\cA(\cM; \cC)$};
    60 \node[blue] (skein) at (4,0) {$\cA(\cM; \cC)$};
    58 \node[below=5pt, description] (skein-label) at (skein) {(the usual TQFT Hilbert space)};
    61 \node[below=5pt, description] (skein-label) at (skein) {(the usual TQFT Hilbert space)};
    59 \path[->](blobs) edge node[above] {$*= 0$} (skein);
    62 \path[->](blobs) edge node[above] {$*= 0$} (skein);
    60 }
    63 }
    61 
    64 
    62 \uncover<2>{
    65 \uncover<3>{
    63   \node[blue] (hoch) at (0,3) {$HH_*(\cC)$};
    66   \node[blue] (hoch) at (0,3) {$HH_*(\cC)$};
    64   \node[right=20pt, description] (hoch-label) at (hoch) {(the Hochschild homology)};
    67   \node[right=20pt, description] (hoch-label) at (hoch) {(the Hochschild homology)};
    65   \path[->](blobs) edge node[right] {$\cM = S^1$} (hoch);
    68   \path[->](blobs) edge node[right] {$\cM = S^1$} (hoch);
    66 }
    69 }
    67 
    70 
    68 \uncover<3>{
    71 \uncover<4>{
    69   \node[blue] (comm) at (-2.4, -1.8) {$H_*(\Delta^\infty(\cM), k)$};
    72   \node[blue] (comm) at (-2.4, -1.8) {$H_*(\Delta^\infty(\cM), k)$};
    70   \node[description, below=5pt] (comm-label) at (comm) {(singular homology of the infinite configuration space)};
    73   \node[description, below=5pt] (comm-label) at (comm) {(singular homology of the infinite configuration space)};
    71   \path[->](blobs) edge node[right=5pt] {$\cC = k[t]$} (comm);
    74   \path[->](blobs) edge node[right=5pt] {$\cC = k[t]$} (comm);
    72 }
    75 }
    73 
    76 
    74 \end{tikzpicture}
    77 \end{tikzpicture}
    75 \end{frame}
    78 \end{frame}
    76 
    79 
       
    80 \begin{frame}{Motivation: Khovanov homology as a $4$d TQFT}
       
    81 \begin{thm}
       
    82 Khovanov homology gives a $4$-category:
       
    83 \begin{description}
       
    84 \item[3-morphisms] tangles, with the usual $3$ operations,
       
    85 \item[4-morphisms] $\Hom{Kh}{T_1}{T_2} = Kh(T_1 \cup \bar{T_2})$, composition defined by saddle cobordisms
       
    86 \end{description}
       
    87 \end{thm}
       
    88 \begin{block}{}
       
    89 There is a corresponding $4$-manifold invariant. Given $L \subset \bdy W^4$, it associates a doubly-graded vector space $\cA(W, L; Kh)$.
       
    90 $$\cA(B^4, L; Kh) \iso Kh(L)$$
       
    91 \end{block}
       
    92 \end{frame}
       
    93 
       
    94 \begin{frame}{Computations are hard}
       
    95 \begin{block}{}
       
    96 The corresponding $4$-manifold invariant is hard to compute, because the TQFT skein module construction breaks the exact triangle for resolving a crossing.
       
    97 \vspace{-0.3cm}
       
    98 \begin{align*}
       
    99 \begin{tikzpicture}
       
   100 \node(a) at (0,0) {$Kh\left(\begin{tikzpicture}[baseline=-2.5pt, scale=0.5, line width=1.5pt]
       
   101 \node[outer sep=-1pt] (x) at (0,0){};
       
   102     \draw (x.45)-- (.5,.5);
       
   103     \draw (x.135) -- (-.5,.5);
       
   104     \draw (x.315) -- (.5,-.5);
       
   105     \draw (x.45) -- (-.5,-.5);
       
   106 \end{tikzpicture}\right)$};
       
   107 \node(b) at (-1.2,-1.5) {$Kh\left(\begin{tikzpicture}[baseline=-2.5pt, scale=0.5, line width=1.5pt]
       
   108     \draw (1.5,.5) .. controls (2,0) .. (1.5,-.5);
       
   109     \draw (2.5,.5) .. controls (2,0) .. (2.5,-.5);
       
   110 \end{tikzpicture}\right)$};
       
   111 \node(c) at (1.2,-1.5) {$Kh\left(\begin{tikzpicture}[baseline=-2.5pt, scale=0.5, line width=1.5pt]
       
   112     \draw (3.5,.5) .. controls (4,0) .. (4.5,.5);
       
   113     \draw (3.5,-.5) .. controls (4,0) .. (4.5,-.5);
       
   114 \end{tikzpicture}\right)$};
       
   115 \draw[->] (a) -- (b);
       
   116 \draw[->] (b) -- (c);
       
   117 \draw[->] (c) -- (a);
       
   118 \end{tikzpicture}
       
   119 \qquad \qquad
       
   120 \begin{tikzpicture}
       
   121 \node(a) at (0,0) {$\cA\left(M, \begin{tikzpicture}[baseline=-2.5pt, scale=0.5, line width=1.5pt]
       
   122 \node[outer sep=-1pt] (x) at (0,0){};
       
   123     \draw (x.45)-- (.5,.5);
       
   124     \draw (x.135) -- (-.5,.5);
       
   125     \draw (x.315) -- (.5,-.5);
       
   126     \draw (x.45) -- (-.5,-.5);
       
   127 \end{tikzpicture}\right)$};
       
   128 \node(b) at (-1.4,-1.5) {$\cA\left(M, \begin{tikzpicture}[baseline=-2.5pt, scale=0.5, line width=1.5pt]
       
   129     \draw (1.5,.5) .. controls (2,0) .. (1.5,-.5);
       
   130     \draw (2.5,.5) .. controls (2,0) .. (2.5,-.5);
       
   131 \end{tikzpicture}\right)$};
       
   132 \node(c) at (1.4,-1.5) {$\cA\left(M,\begin{tikzpicture}[baseline=-2.5pt, scale=0.5, line width=1.5pt]
       
   133     \draw (3.5,.5) .. controls (4,0) .. (4.5,.5);
       
   134     \draw (3.5,-.5) .. controls (4,0) .. (4.5,-.5);
       
   135 \end{tikzpicture}\right)$};
       
   136 \node at (0,-0.75) {\Large \color{red} ?};
       
   137 \draw[dashed] (a) -- (b);
       
   138 \draw[dashed] (b) -- (c);
       
   139 \draw[dashed] (c) -- (a);
       
   140 \end{tikzpicture}
       
   141 \end{align*}\vspace{-1cm}
       
   142 \end{block}
       
   143 There is a spectral sequence converging to $0$ relating the blob homologies for the triangle of resolutions. 
       
   144 \begin{conj}
       
   145 It may be possible to compute the skein module
       
   146 %$$\cA(W, L; Kh) = H_0(\bc_*(W, L; Kh))$$
       
   147 by first computing the entire blob homology.
       
   148 \end{conj}
       
   149 \end{frame}
       
   150 
    77 \begin{frame}{$n$-categories}
   151 \begin{frame}{$n$-categories}
    78 \begin{block}{Defining $n$-categories is fraught with difficulties}
   152 \begin{block}{Defining $n$-categories is fraught with difficulties}
    79 I'm not going to go into details; I'll draw $2$-dimensional pictures, and rely on your intuition for pivotal $2$-categories.
   153 For now, I'm not going to go into details; I'll draw $2$-dimensional pictures, and rely on your intuition for pivotal $2$-categories.
    80 \end{block}
   154 \end{block}
    81 \begin{block}{}
   155 \begin{block}{}
    82 Kevin's talk (part $\mathbb{II}$) will explain the notions of `topological $n$-categories' and `$A_\infty$ $n$-categories'.
   156 Later, I'll explain the notions of `topological $n$-categories' and `$A_\infty$ $n$-categories'.
    83 \end{block}
   157 \end{block}
    84 
   158 
    85 \begin{block}{}
   159 \begin{block}{}
    86 \begin{itemize}
   160 \begin{itemize}
    87 \item
   161 \item
   100 \begin{frame}{Fields and pasting diagrams}
   174 \begin{frame}{Fields and pasting diagrams}
   101 \begin{block}{Pasting diagrams}
   175 \begin{block}{Pasting diagrams}
   102 Fix an $n$-category with strong duality $\cC$. A \emph{field} on $\cM$ is a pasting diagram drawn on $\cM$, with cells labelled by morphisms from $\cC$.
   176 Fix an $n$-category with strong duality $\cC$. A \emph{field} on $\cM$ is a pasting diagram drawn on $\cM$, with cells labelled by morphisms from $\cC$.
   103 \end{block}
   177 \end{block}
   104 \begin{example}[$\cC = \text{TL}_d$ the Temperley-Lieb category]
   178 \begin{example}[$\cC = \text{TL}_d$ the Temperley-Lieb category]
   105 $$\roundframe{\mathfig{0.35}{definition/example-pasting-diagram}} \in \cF^{\text{TL}_d}\left(T^2\right)$$
   179 $$\roundframe{\mathfig{0.35}{definition/example-pasting-diagram}} \in \cF\left(T^2\right)$$
   106 \end{example}
   180 \end{example}
   107 \begin{block}{}
   181 \begin{block}{}
   108 Given a pasting diagram on a ball, we can evaluate it to a morphism. We call the kernel the \emph{null fields}.
   182 Given a pasting diagram on a ball, we can evaluate it to a morphism. We call the kernel the \emph{null fields}.
   109 \vspace{-3mm}
   183 \vspace{-3mm}
   110 $$\text{ev}\Bigg(\roundframe{\mathfig{0.12}{definition/evaluation1}} - \frac{1}{d}\roundframe{\mathfig{0.12}{definition/evaluation2}}\Bigg) = 0$$
   184 $$\text{ev}\Bigg(\roundframe{\mathfig{0.12}{definition/evaluation1}} - \frac{1}{d}\roundframe{\mathfig{0.12}{definition/evaluation2}}\Bigg) = 0$$
   138 \begin{frame}{\emph{Definition} of the blob complex, $k=0,1$}
   212 \begin{frame}{\emph{Definition} of the blob complex, $k=0,1$}
   139 \begin{block}{Motivation}
   213 \begin{block}{Motivation}
   140 A \emph{local} construction, such that when $\cM$ is a ball, $\bc_*(\cM; \cC)$ is a resolution of $\cA(\cM,; \cC)$.
   214 A \emph{local} construction, such that when $\cM$ is a ball, $\bc_*(\cM; \cC)$ is a resolution of $\cA(\cM,; \cC)$.
   141 \end{block}
   215 \end{block}
   142 
   216 
       
   217 \mode<handout>{\vspace{-5mm}}
   143 \begin{block}{}
   218 \begin{block}{}
   144 \center
   219 \center
   145 $\bc_0(\cM; \cC) = \cF(\cM)$, arbitrary pasting diagrams on $\cM$.
   220 $\bc_0(\cM; \cC) = \cF(\cM)$, arbitrary pasting diagrams on $\cM$.
   146 \end{block}
   221 \end{block}
   147 
   222 
   151 \end{block}
   226 \end{block}
   152 \vspace{-3.5mm}
   227 \vspace{-3.5mm}
   153 $$\mathfig{.5}{definition/single-blob}$$
   228 $$\mathfig{.5}{definition/single-blob}$$
   154 \vspace{-3mm}
   229 \vspace{-3mm}
   155 \begin{block}{}
   230 \begin{block}{}
       
   231 \mode<handout>{\vspace{-5mm}}
   156 \vspace{-6mm}
   232 \vspace{-6mm}
   157 \begin{align*}
   233 \begin{align*}
   158 d_1 : (B, u, r) & \mapsto u \circ r & \bc_0 / \im(d_1) \iso A(\cM; \cC)
   234 d_1 : (B, u, r) & \mapsto u \circ r & \bc_0 / \im(d_1) \iso A(\cM; \cC)
   159 \end{align*}
   235 \end{align*}
   160 \end{block}
   236 \end{block}
   161 \end{frame}
   237 \end{frame}
   162 
   238 
   163 \begin{frame}{Definition, $k=2$}
   239 \begin{frame}{Definition, $k=2$}
   164 \begin{block}{}
   240 \begin{block}{}
   165 \vspace{-1mm}
   241 \vspace{-1mm}
       
   242 \mode<handout>{\vspace{-5mm}}
   166 $$\bc_2 = \bc_2^{\text{disjoint}} \oplus \bc_2^{\text{nested}}$$
   243 $$\bc_2 = \bc_2^{\text{disjoint}} \oplus \bc_2^{\text{nested}}$$
   167 \end{block}
   244 \end{block}
   168 \begin{block}{}
   245 \begin{block}{}
       
   246 \mode<handout>{\vspace{-5mm}}
   169 \vspace{-5mm}
   247 \vspace{-5mm}
   170 \begin{align*}
   248 \begin{align*}
   171 \bc_2^{\text{disjoint}} & =  \Complex\setcl{\roundframe{\mathfig{0.5}{definition/disjoint-blobs}}}{\text{ev}_{B_i}(u_i) = 0}
   249 \bc_2^{\text{disjoint}} & =  \Complex\setcl{\roundframe{\mathfig{0.5}{definition/disjoint-blobs}}}{\text{ev}_{B_i}(u_i) = 0}
   172 \end{align*}
   250 \end{align*}
   173 \vspace{-4mm}
   251 \vspace{-4mm}
   198 \begin{frame}{Hochschild homology}
   276 \begin{frame}{Hochschild homology}
   199 \begin{block}{TQFT on $S^1$ is `coinvariants'}
   277 \begin{block}{TQFT on $S^1$ is `coinvariants'}
   200 \vspace{-3mm}
   278 \vspace{-3mm}
   201 $$\cA(S^1, A) = \Complex\set{\roundframe{\mathfig{0.1}{hochschild/m-a-b}}}\scalebox{2}{$/$}\set{\roundframe{\mathfig{0.065}{hochschild/ma}} - \roundframe{\mathfig{0.12}{hochschild/m-a}}} = A/(ab-ba)$$
   279 $$\cA(S^1, A) = \Complex\set{\roundframe{\mathfig{0.1}{hochschild/m-a-b}}}\scalebox{2}{$/$}\set{\roundframe{\mathfig{0.065}{hochschild/ma}} - \roundframe{\mathfig{0.12}{hochschild/m-a}}} = A/(ab-ba)$$
   202 \end{block}
   280 \end{block}
       
   281 \mode<handout>{\vspace{-3mm}}
   203 \begin{block}{}
   282 \begin{block}{}
   204 The Hochschild complex is `coinvariants of the bar resolution'
   283 The Hochschild complex is `coinvariants of the bar resolution'
   205 \vspace{-2mm}
   284 \vspace{-2mm}
   206 $$ \cdots \to A \tensor A \tensor A \to A \tensor A \xrightarrow{m \tensor a \mapsto ma-am} A$$
   285 $$ \cdots \to A \tensor A \tensor A \to A \tensor A \xrightarrow{m \tensor a \mapsto ma-am} A$$
   207 \end{block}
   286 \end{block}
   222 $$\CH{\cM} \tensor \bc_*(\cM) \to \bc_*(\cM).$$
   301 $$\CH{\cM} \tensor \bc_*(\cM) \to \bc_*(\cM).$$
   223 which is associative up to homotopy, and compatible with gluing.
   302 which is associative up to homotopy, and compatible with gluing.
   224 \end{thm}
   303 \end{thm}
   225 \begin{block}{}
   304 \begin{block}{}
   226 Taking $H_0$, this is the mapping class group acting on a TQFT skein module.
   305 Taking $H_0$, this is the mapping class group acting on a TQFT skein module.
   227 \end{block}
       
   228 \end{frame}
       
   229 
       
   230 \begin{frame}{Higher Deligne conjecture}
       
   231 \begin{block}{Deligne conjecture}
       
   232 Chains on the little discs operad acts on Hochschild cohomology.
       
   233 \end{block}
       
   234 
       
   235 \begin{block}{}
       
   236 Call $\Hom{A_\infty}{\bc_*(\cM)}{\bc_*(\cM)}$ `blob cochains on $\cM$'.
       
   237 \end{block}
       
   238 
       
   239 \begin{block}{Theorem* (Higher Deligne conjecture)}
       
   240 \scalebox{0.96}{Chains on the $n$-dimensional fat graph operad acts on blob cochains.}
       
   241 \vspace{-3mm}
       
   242 $$\mathfig{.85}{deligne/manifolds}$$
       
   243 \end{block}
   306 \end{block}
   244 \end{frame}
   307 \end{frame}
   245 
   308 
   246 \begin{frame}{Gluing}
   309 \begin{frame}{Gluing}
   247 \begin{block}{$\bc_*(Y \times [0,1])$ is naturally an $A_\infty$ category}
   310 \begin{block}{$\bc_*(Y \times [0,1])$ is naturally an $A_\infty$ category}
   260 	\bc_*(X \bigcup_Y \selfarrow) \iso \bc_*(X) \bigotimes_{\bc_*(Y)}^{A_\infty} \selfarrow.
   323 	\bc_*(X \bigcup_Y \selfarrow) \iso \bc_*(X) \bigotimes_{\bc_*(Y)}^{A_\infty} \selfarrow.
   261 \]
   324 \]
   262 \end{thm}
   325 \end{thm}
   263 In principle, we can compute blob homology from a handle decomposition, by iterated Hochschild homology.
   326 In principle, we can compute blob homology from a handle decomposition, by iterated Hochschild homology.
   264 \end{frame}
   327 \end{frame}
       
   328 
       
   329 \begin{frame}{Higher Deligne conjecture}
       
   330 \begin{block}{Deligne conjecture}
       
   331 Chains on the little discs operad acts on Hochschild cohomology.
       
   332 \end{block}
       
   333 
       
   334 \begin{block}{}
       
   335 Call $\Hom{\bc_*(\bdy M)}{\bc_*(\cM)}{\bc_*(\cM)}$ `blob cochains on $\cM$'.
       
   336 \end{block}
       
   337 
       
   338 \begin{block}{Theorem (Higher Deligne conjecture)}
       
   339 \scalebox{0.96}{Chains on the $n$-dimensional fat graph operad acts on blob cochains.}
       
   340 \vspace{-3mm}
       
   341 $$\mathfig{.85}{deligne/manifolds}$$
       
   342 \end{block}
       
   343 \end{frame}
       
   344 
       
   345 \begin{frame}{Maps to a space}
       
   346 \begin{block}{}
       
   347 Fix a target space $T$. There is an $A_\infty$ $n$-category $\pi_{\leq n}^\infty(T)$ defined by
       
   348 $$\pi_{\leq n}^\infty(T)(B) = C_*(\Maps(B\to T)).$$
       
   349 \end{block}
       
   350 \begin{thm}
       
   351 The blob complex recovers mapping spaces:
       
   352 $$\bc_*(M; \pi_{\leq n}^\infty(T)) \iso C_*(\Maps(M \to T))$$
       
   353 \end{thm}
       
   354 This generalizes  a result of Lurie: if $T$ is $n-1$ connected, $\pi_{\leq n}^\infty(T)$ is an $E_n$-algebra and the blob complex is the same as his topological chiral homology.
       
   355 \end{frame}
       
   356 
   265 \end{document}
   357 \end{document}
   266 % ----------------------------------------------------------------
   358 % ----------------------------------------------------------------
   267 
   359