diff -r 675f53735445 -r 1d76e832d32f text/basic_properties.tex --- a/text/basic_properties.tex Fri Jun 04 17:00:18 2010 -0700 +++ b/text/basic_properties.tex Fri Jun 04 17:15:53 2010 -0700 @@ -3,9 +3,15 @@ \section{Basic properties of the blob complex} \label{sec:basic-properties} -In this section we complete the proofs of Properties 2-4. Throughout the paper, where possible, we prove results using Properties 1-4, rather than the actual definition of blob homology. This allows the possibility of future improvements to or alternatives on our definition. In fact, we hope that there may be a characterisation of blob homology in terms of Properties 1-4, but at this point we are unaware of one. +In this section we complete the proofs of Properties 2-4. +Throughout the paper, where possible, we prove results using Properties 1-4, +rather than the actual definition of blob homology. +This allows the possibility of future improvements to or alternatives on our definition. +In fact, we hope that there may be a characterisation of blob homology in +terms of Properties 1-4, but at this point we are unaware of one. -Recall Property \ref{property:disjoint-union}, that there is a natural isomorphism $\bc_*(X \du Y) \cong \bc_*(X) \otimes \bc_*(Y)$. +Recall Property \ref{property:disjoint-union}, +that there is a natural isomorphism $\bc_*(X \du Y) \cong \bc_*(X) \otimes \bc_*(Y)$. \begin{proof}[Proof of Property \ref{property:disjoint-union}] Given blob diagrams $b_1$ on $X$ and $b_2$ on $Y$, we can combine them @@ -15,7 +21,9 @@ In the other direction, any blob diagram on $X\du Y$ is equal (up to sign) to one that puts $X$ blobs before $Y$ blobs in the ordering, and so determines a pair of blob diagrams on $X$ and $Y$. -These two maps are compatible with our sign conventions. (We follow the usual convention for tensors products of complexes, as in e.g. \cite{MR1438306}: $d(a \tensor b) = da \tensor b + (-1)^{\deg(a)} a \tensor db$.) +These two maps are compatible with our sign conventions. +(We follow the usual convention for tensors products of complexes, +as in e.g. \cite{MR1438306}: $d(a \tensor b) = da \tensor b + (-1)^{\deg(a)} a \tensor db$.) The two maps are inverses of each other. \end{proof} @@ -43,7 +51,8 @@ Define $h_0 : \bc_0(B^n; c) \to \bc_1(B^n; c)$ by setting $h_0(x)$ equal to the 1-blob with blob $B^n$ and label $x - s(p(x)) \in U(B^n; c)$. \end{proof} -This proves Property \ref{property:contractibility} (the second half of the statement of this Property was immediate from the definitions). +This proves Property \ref{property:contractibility} (the second half of the +statement of this Property was immediate from the definitions). Note that even when there is no splitting $s$, we can let $h_0 = 0$ and get a homotopy equivalence to the 2-step complex $U(B^n; c) \to \cC(B^n; c)$. @@ -92,7 +101,8 @@ Given compatible fields (boundary conditions) $a$, $b$ and $c$ on $Y$, $-Y$ and $Z$, we have the blob complex $\bc_*(X; a, b, c)$. If $b = -a$ (the orientation reversal of $a$), then we can glue up blob diagrams on -$X$ to get blob diagrams on $X\sgl$. This proves Property \ref{property:gluing-map}, which we restate here in more detail. +$X$ to get blob diagrams on $X\sgl$. +This proves Property \ref{property:gluing-map}, which we restate here in more detail. \textbf{Property \ref{property:gluing-map}.}\emph{ There is a natural chain map