text/blobdef.tex
changeset 491 045e01f63729
parent 490 e9ef2270eb61
child 506 4a23163843a9
equal deleted inserted replaced
490:e9ef2270eb61 491:045e01f63729
    65 where $u\bullet r$ denotes the field on $X$ obtained by gluing $u$ to $r$.
    65 where $u\bullet r$ denotes the field on $X$ obtained by gluing $u$ to $r$.
    66 In other words $\bd : \bc_1(X) \to \bc_0(X)$ is given by
    66 In other words $\bd : \bc_1(X) \to \bc_0(X)$ is given by
    67 just erasing the blob from the picture
    67 just erasing the blob from the picture
    68 (but keeping the blob label $u$).
    68 (but keeping the blob label $u$).
    69 
    69 
    70 \nn{it seems rather strange to make this a theorem}
    70 \nn{it seems rather strange to make this a theorem} \nn{it's a theorem because it's stated in the introduction, and I wanted everything there to have numbers that pointed into the paper --S}
    71 Note that directly from the definition we have
    71 Note that directly from the definition we have
    72 \begin{thm}
    72 \begin{thm}
    73 \label{thm:skein-modules}
    73 \label{thm:skein-modules}
    74 The skein module $A(X)$ is naturally isomorphic to $\bc_0(X)/\bd(\bc_1(X))) = H_0(\bc_*(X))$.
    74 The skein module $A(X)$ is naturally isomorphic to $\bc_0(X)/\bd(\bc_1(X))) = H_0(\bc_*(X))$.
    75 \end{thm}
    75 \end{thm}
   149 \item If $X'$ is obtained from $X$ by gluing, then any permissible configuration of blobs
   149 \item If $X'$ is obtained from $X$ by gluing, then any permissible configuration of blobs
   150 on $X$ gives rise to a permissible configuration on $X'$.
   150 on $X$ gives rise to a permissible configuration on $X'$.
   151 (This is necessary for Proposition \ref{blob-gluing}.)
   151 (This is necessary for Proposition \ref{blob-gluing}.)
   152 \end{itemize}
   152 \end{itemize}
   153 Combining these two operations can give rise to configurations of blobs whose complement in $X$ is not
   153 Combining these two operations can give rise to configurations of blobs whose complement in $X$ is not
   154 a manifold. \todo{example}
   154 a manifold.
   155 Thus will need to be more careful when speaking of a field $r$ on the complement of the blobs.
   155 Thus will need to be more careful when speaking of a field $r$ on the complement of the blobs.
   156 
   156 
   157 \begin{example}
   157 \begin{example}
   158 Consider the four subsets of $\Real^3$,
   158 Consider the four subsets of $\Real^3$,
   159 \begin{align*}
   159 \begin{align*}
   238 \item $p(\bar{b}) = \kone(p(b))$, where $\bar{b}$ is obtained from $b$ by adding an outer blob which 
   238 \item $p(\bar{b}) = \kone(p(b))$, where $\bar{b}$ is obtained from $b$ by adding an outer blob which 
   239 encloses all the others (equivalently, add a new edge to the root, with the new vertex becoming the root).
   239 encloses all the others (equivalently, add a new edge to the root, with the new vertex becoming the root).
   240 \end{itemize}
   240 \end{itemize}
   241 For example, a diagram of $k$ strictly nested blobs corresponds to a $k$-simplex, while
   241 For example, a diagram of $k$ strictly nested blobs corresponds to a $k$-simplex, while
   242 a diagram of $k$ disjoint blobs corresponds to a $k$-cube.
   242 a diagram of $k$ disjoint blobs corresponds to a $k$-cube.
   243 (This correspondence works best if we think of each twig label $u_i$ as having the form
   243 (When the fields come from an $n$-category, this correspondence works best if we think of each twig label $u_i$ as having the form
   244 $x - s(e(x))$, where $x$ is an arbitrary field on $B_i$, $e: \cF(B_i) \to C$ is the evaluation map, 
   244 $x - s(e(x))$, where $x$ is an arbitrary field on $B_i$, $e: \cF(B_i) \to C$ is the evaluation map, 
   245 and $s:C \to \cF(B_i)$ is some fixed section of $e$. \todo{This parenthetical remark mysteriously specialises to the category case})
   245 and $s:C \to \cF(B_i)$ is some fixed section of $e$.)
   246 
   246 
   247 
   247