text/a_inf_blob.tex
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    16 \medskip
    16 \medskip
    17 
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    18 An important technical tool in the proofs of this section is provided by the idea of `small blobs'.
    18 An important technical tool in the proofs of this section is provided by the idea of `small blobs'.
    19 Fix $\cU$, an open cover of $M$.
    19 Fix $\cU$, an open cover of $M$.
    20 Define the `small blob complex' $\bc^{\cU}_*(M)$ to be the subcomplex of $\bc_*(M)$ of all blob diagrams in which every blob is contained in some open set of $\cU$. 
    20 Define the `small blob complex' $\bc^{\cU}_*(M)$ to be the subcomplex of $\bc_*(M)$ of all blob diagrams in which every blob is contained in some open set of $\cU$, and moreover each field labeling a region cut out by the blobs is splittable into fields on smaller regions, each of which is contained in some open set.
    21 \nn{KW: We need something a little stronger: Every blob diagram (even a 0-blob diagram) is splittable into pieces which are small w.r.t.\ $\cU$.
       
    22 If field have potentially large coupons/boxes, then this is a non-trivial constraint.
       
    23 On the other hand, we could probably get away with ignoring this point.
       
    24 Maybe the exposition will be better if we sweep this technical detail under the rug?}
       
    25 
    21 
    26 \begin{thm}[Small blobs] \label{thm:small-blobs}
    22 \begin{thm}[Small blobs] \label{thm:small-blobs}
    27 The inclusion $i: \bc^{\cU}_*(M) \into \bc_*(M)$ is a homotopy equivalence.
    23 The inclusion $i: \bc^{\cU}_*(M) \into \bc_*(M)$ is a homotopy equivalence.
    28 \end{thm}
    24 \end{thm}
    29 The proof appears in \S \ref{appendix:small-blobs}.
    25 The proof appears in \S \ref{appendix:small-blobs}.