What fraction of an S-orbit can lie on a hyperplane?

Autor: Matthew Satriano, Jiahui Huang, David McKinnon
Rok vydání: 2021
Předmět:
Zdroj: Linear Algebra and its Applications. 613:1-23
ISSN: 0024-3795
Popis: Consider the S n -action on R n given by permuting coordinates. This paper addresses the following problem: compute max v , H ⁡ | H ∩ S n v | as H ⊂ R n ranges over all hyperplanes through the origin and v ∈ R n ranges over all vectors with distinct coordinates that are not contained in the hyperplane ∑ x i = 0 . We conjecture that for n ≥ 3 , the answer is ( n − 1 ) ! for odd n, and n ( n − 2 ) ! for even n. We prove that if p is the largest prime with p ≤ n , then max v , H ⁡ | H ∩ S n v | ≤ n ! p . In particular, this proves the conjecture when n or n − 1 is prime.
Databáze: OpenAIRE