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Upper Bound for the Coefficients of Chromatic polynomials

组合数学 2007-05-23 v1

摘要

This paper describes an improvement in the upper bound for the magnitude of a coefficient of a term in the chromatic polynomial of a general graph. If ara_r is the coefficient of the qrq^r term in the chromatic polynomial P(G,q)P(G,q), where qq is the number of colors, then we find ar(evr)(eg+2vrg+2)+(ekgg+2vrg+2)n=1kggm=1g1(eg+1nmvrg)δg,3n=1kg+g+1g(egg+1nvrg)a_r \le {e \choose v-r} - {e-g+2 \choose v-r-g+2} + {e-k_g-g+2 \choose v-r-g+2} - \sum _{n=1}^{k_g-\ell_g}\sum_{m=1}^{\ell_g-1} {e-g+1-n-m \choose v-r-g} - \delta_{g,3}\sum_{n=1}^{k_g+\ell_{g+1}^*-\ell_g} {e-\ell_g-g+1-n \choose v-r-g}, where kgk_g is the number of circuits of length gg and g\ell_g and g+1\ell_{g+1}^* are certain numbers defined in the text.

关键词

引用

@article{arxiv.math/0102214,
  title  = {Upper Bound for the Coefficients of Chromatic polynomials},
  author = {Shu-Chiuan Chang},
  journal= {arXiv preprint arXiv:math/0102214},
  year   = {2007}
}

备注

9 pages, Latex