Interlacing Log-concavity of the Boros-Moll Polynomials

Abstract

We introduce the notion of interlacing log-concavity of a polynomial sequence $\{P_m(x){\}}_{m\ge 0}$, where $P_m(x)$ is a polynomial of degree m with positive coefficients $a_i(m)$. This sequence of polynomials is said to be interlacing log-concave if the ratios of consecutive coefficients of $P_m(x)$ interlace the ratios of consecutive coefficients of $P_{m+1}(x)$ for any $m\ge 0$. Interlacing log-concavity is stronger than the log-concavity. We show that the Boros-Moll polynomials are interlacing log-concave. Furthermore we give a sufficient condition for interlacing log-concavity which implies that some classical combinatorial polynomials are interlacing log-concave.

10 pages