Distinct permutation dot products

Fuente: arXiv
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Main Author: Pohoata, Cosmin
Format: Preprint
Published: 2026
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author Pohoata, Cosmin
author_facet Pohoata, Cosmin
contents We show that for any two sets of reals numbers $A=\{a_1,\dots,a_n\}$ and $B=\{b_1,\dots,b_n\}$, the sums of the form $\sum_{i=1}^n a_i\,b_{π(i)}$ always take on $Ω(n^{3})$ distinct values, as we range over all permutations $π\in S_n$. An important ingredient is a ``supportive'' version of Halász's anticoncentration theorem from Littlewood-Offord theory, which may be of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2601_12445
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Distinct permutation dot products
Pohoata, Cosmin
Combinatorics
We show that for any two sets of reals numbers $A=\{a_1,\dots,a_n\}$ and $B=\{b_1,\dots,b_n\}$, the sums of the form $\sum_{i=1}^n a_i\,b_{π(i)}$ always take on $Ω(n^{3})$ distinct values, as we range over all permutations $π\in S_n$. An important ingredient is a ``supportive'' version of Halász's anticoncentration theorem from Littlewood-Offord theory, which may be of independent interest.
title Distinct permutation dot products
topic Combinatorics
url https://arxiv.org/abs/2601.12445