# HG changeset patch # User Kevin Walker # Date 1323280978 28800 # Node ID cd26c49d673cc58e948eed31fef965b1df4fa272 # Parent bfae3636133ee59dbd81b8d3b77e64cb3175069a C -> D in C.2 diff -r bfae3636133e -r cd26c49d673c text/appendixes/comparing_defs.tex --- a/text/appendixes/comparing_defs.tex Fri Dec 02 22:09:48 2011 -0800 +++ b/text/appendixes/comparing_defs.tex Wed Dec 07 10:02:58 2011 -0800 @@ -123,7 +123,7 @@ \subsection{Pivotal 2-categories} \label{ssec:2-cats} Let $\cC$ be a disk-like 2-category. -We will construct from $\cC$ a traditional pivotal 2-category. +We will construct from $\cC$ a traditional pivotal 2-category $D$. (The ``pivotal" corresponds to our assumption of strong duality for $\cC$.) We will try to describe the construction in such a way that the generalization to $n>2$ is clear, @@ -134,21 +134,21 @@ Each approach has advantages and disadvantages. For better or worse, we choose bigons here. -Define the $k$-morphisms $C^k$ of $C$ to be $\cC(B^k) \trans E$, where $B^k$ denotes the standard +Define the $k$-morphisms $D^k$ of $D$ to be $\cC(B^k) \trans E$, where $B^k$ denotes the standard $k$-ball, which we also think of as the standard bihedron (a.k.a.\ globe). (For $k=1$ this is an interval, and for $k=2$ it is a bigon.) Since we are thinking of $B^k$ as a bihedron, we have a standard decomposition of the $\bd B^k$ into two copies of $B^{k-1}$ which intersect along the ``equator" $E \cong S^{k-2}$. Recall that the subscript in $\cC(B^k) \trans E$ means that we consider the subset of $\cC(B^k)$ whose boundary is splittable along $E$. -This allows us to define the domain and range of morphisms of $C$ using +This allows us to define the domain and range of morphisms of $D$ using boundary and restriction maps of $\cC$. -Choosing a homeomorphism $B^1\cup B^1 \to B^1$ defines a composition map on $C^1$. +Choosing a homeomorphism $B^1\cup B^1 \to B^1$ defines a composition map on $D^1$. This is not associative, but we will see later that it is weakly associative. Choosing a homeomorphism $B^2\cup B^2 \to B^2$ defines a ``vertical" composition map -on $C^2$ (Figure \ref{fzo1}). +on $D^2$ (Figure \ref{fzo1}). Isotopy invariance implies that this is associative. We will define a ``horizontal" composition later. @@ -203,7 +203,7 @@ \label{fzo1} \end{figure} -Given $a\in C^1$, define $\id_a = a\times I \in C^2$ (pinched boundary). +Given $a\in D^1$, define $\id_a = a\times I \in D^2$ (pinched boundary). Extended isotopy invariance for $\cC$ shows that this morphism is an identity for vertical composition.