Semidefinite programming bounds for binary codes and coloring<BR>

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Monique Laurent<BR>
CWI, Amsterdam<BR>

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Abstract: <BR>

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We investigate semidefinite programming approximations for the
stability number and the coloring number of a graph and,
in particular, how they apply to Hamming graphs.
Our bounds improve the classic theta number of
Lovasz (corresponding to Delsarte bound) as well as the recent
bound of Schrijver for codes. Their computation relies on exploiting 
symmetries and using the block-diagonalization of the Terwilliger
algebra.