text/blobdef.tex
changeset 219 7e9a7b9605d3
parent 216 1b3ebb7793c9
child 222 217b6a870532
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   197 \begin{itemize}
   197 \begin{itemize}
   198 \item $p(\emptyset) = pt$, where $\emptyset$ denotes a 0-blob diagram or empty tree;
   198 \item $p(\emptyset) = pt$, where $\emptyset$ denotes a 0-blob diagram or empty tree;
   199 \item $p(a \du b) = p(a) \times p(b)$, where $a \du b$ denotes the distant (non-overlapping) union of two blob diagrams (equivalently, join two trees at the roots); and
   199 \item $p(a \du b) = p(a) \times p(b)$, where $a \du b$ denotes the distant (non-overlapping) union of two blob diagrams (equivalently, join two trees at the roots); and
   200 \item $p(\bar{b}) = \kone(p(b))$, where $\bar{b}$ is obtained from $b$ by adding an outer blob which encloses all the others.
   200 \item $p(\bar{b}) = \kone(p(b))$, where $\bar{b}$ is obtained from $b$ by adding an outer blob which encloses all the others.
   201 \end{itemize}
   201 \end{itemize}
   202 (This correspondence works best if we thing of each twig label $u_i$ as being a difference of
       
   203 two fields.)
       
   204 For example, a diagram of $k$ strictly nested blobs corresponds to a $k$-simplex, while
   202 For example, a diagram of $k$ strictly nested blobs corresponds to a $k$-simplex, while
   205 a diagram of $k$ disjoint blobs corresponds to a $k$-cube.
   203 a diagram of $k$ disjoint blobs corresponds to a $k$-cube.
   206 
   204 (This correspondence works best if we thing of each twig label $u_i$ as having the form
   207 
   205 $x - s(e(x))$, where $x$ is an arbitrary field on $B_i$, $e: \cC(B_i) \to C$ is the evaluation map, 
       
   206 and $s:C \to \cC(B_i)$ is some fixed section of $e$.)
       
   207 
       
   208