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Random Weighting, Asymptotic Counting, and Inverse Isoperimetry

Alexander Barvinok·Alex Samorodnitsky
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Abstract

For a family X of k-subsets of the set 1,...,n, let |X| be the cardinality of X and let Gamma(X,mu) be the expected maximum weight of a subset from X when the weights of 1,...,n are chosen independently at random from a symmetric probability distribution mu on R. We consider the inverse isoperimetric problem of finding mu for which Gamma(X,mu) gives the best estimate of ln|X|. We prove that the optimal choice of mu is the logistic distribution, in which case Gamma(X,mu) provides an asymptotically tight estimate of ln|X| as k^{-1}ln|X| grows. Since in many important cases Gamma(X,mu) can be easily computed, we obtain computationally efficient approximation algorithms for a variety of counting problems. Given mu, we describe families X of a given cardinality with the minimum value of Gamma(X,mu), thus extending and sharpening various isoperimetric inequalities in the Boolean cube.

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Alexander Barvinok, Alex Samorodnitsky. 2003-06-04. Random Weighting, Asymptotic Counting, and Inverse Isoperimetry. https://arxiv.org/abs/math/0302177

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