diff -r 787914e9e859 -r ec8587c33c0b text/appendixes/comparing_defs.tex --- a/text/appendixes/comparing_defs.tex Sat May 28 09:49:30 2011 -0600 +++ b/text/appendixes/comparing_defs.tex Sat May 28 21:45:13 2011 -0600 @@ -43,28 +43,40 @@ Given $a\in c(\cX)^0$, define $\id_a \deq a\times B^1$. By extended isotopy invariance in $\cX$, this has the expected properties of an identity morphism. +We have now defined the basic ingredients for the 1-category $c(\cX)$. +As we explain below, $c(\cX)$ might have additional structure corresponding to the +unoriented, oriented, Spin, $\text{Pin}_+$ or $\text{Pin}_-$ structure on the 1-balls used to define $\cX$. -If the underlying manifolds for $\cX$ have further geometric structure, then we obtain certain functors. -The base case is for oriented manifolds, where we obtain no extra algebraic data. - -For 1-categories based on unoriented manifolds, +For 1-categories based on unoriented balls, there is a map $\dagger:c(\cX)^1\to c(\cX)^1$ coming from $\cX$ applied to an orientation-reversing homeomorphism (unique up to isotopy) from $B^1$ to itself. +(Of course our $B^1$ is unoriented, i.e.\ not equipped with an orientation. +We mean the homeomorphism which would reverse the orientation if there were one; +$B^1$ is not oriented, but it is orientable.) Topological properties of this homeomorphism imply that $a^{\dagger\dagger} = a$ ($\dagger$ is order 2), $\dagger$ reverses domain and range, and $(ab)^\dagger = b^\dagger a^\dagger$ ($\dagger$ is an anti-automorphism). +Recall that in this context 0-balls should be thought of as equipped with a germ of a 1-dimensional neighborhood. +There is a unique such 0-ball, up to homeomorphism, but it has a non-identity automorphism corresponding to reversing the +orientation of the germ. +Consequently, the objects of $c(\cX)$ are equipped with an involution, also denoted $\dagger$. +If $a:x\to y$ is a morphism of $c(\cX)$ then $a^\dagger: y^\dagger\to x^\dagger$. -For 1-categories based on Spin manifolds, +For 1-categories based on oriented balls, there are no non-trivial homeomorphisms of 0- or 1-balls, and thus no +additional structure on $c(\cX)$. + +For 1-categories based on Spin balls, the the nontrivial spin homeomorphism from $B^1$ to itself which covers the identity gives an order 2 automorphism of $c(\cX)^1$. -For 1-categories based on $\text{Pin}_-$ manifolds, +For 1-categories based on $\text{Pin}_-$ balls, we have an order 4 antiautomorphism of $c(\cX)^1$. -For 1-categories based on $\text{Pin}_+$ manifolds, +For 1-categories based on $\text{Pin}_+$ balls, we have an order 2 antiautomorphism and also an order 2 automorphism of $c(\cX)^1$, and these two maps commute with each other. -%\nn{need to also consider automorphisms of $B^0$ / objects} + + \noop{ \medskip