English

Littlewood-Offord problems for the Curie-Weiss models

Probability 2024-11-18 v2

Abstract

In this paper, we consider the Littlewood-Offord problems in one dimension for the Curie-Weiss models. Let Qn+:=supxRsupv1,v2,,vn1P(i=1nviεi(x1,x+1)),Q_n^{+}:=\sup_{x\in\mathbb{R}}\sup_{v_1,v_2,\ldots,v_n\geq 1}P(\sum_{i=1}^{n}v_i\varepsilon_i\in(x-1,x+1)), Qn=supxRsupv1,v2,,vn1P(i=1nviεi(x1,x+1))Q_n=\sup_{x\in\mathbb{R}}\sup_{|v_1|,|v_2|,\ldots,|v_n|\geq 1}P(\sum_{i=1}^{n}v_i\varepsilon_i\in(x-1,x+1)) where the random variables (εi)1in(\varepsilon_i)_{1\leq i\leq n} are spins in Curie-Weiss models. We calculate the asymptotic properties of Qn+Q_n^{+} and QnQ_n as nn\to\infty and observe the phenomena of phase transitions. Meanwhile, we also get that Qn+Q_n^{+} is attained when v1=v2==vn=1v_1=v_2=\cdots=v_n=1. And QnQ_n is attained when one half of (vi)1in(v_i)_{1\leq i\leq n} equals to 11 and the other half equals to 1-1 when nn is even.This is a generalization of classical Littlewood-Offord problems from Rademacher random variables to possibly dependent random variables. In particular, it includes the case of general independent and identically distributed Bernoulli random variables.

Keywords

Cite

@article{arxiv.2408.00127,
  title  = {Littlewood-Offord problems for the Curie-Weiss models},
  author = {Yinshan Chang and Xue Peng},
  journal= {arXiv preprint arXiv:2408.00127},
  year   = {2024}
}