English

Serial Exchanges in Random Bases

Combinatorics 2023-05-03 v1

Abstract

It was conjectured by Kotlar and Ziv that for any two bases B1B_1 and B2B_2 in a matroid MM and any subset XB1X \subset B_1, there is a subset YY and orderings x1x2xkx_1 \prec x_2 \prec \cdots \prec x_k and y1y2yky_1 \prec y_2 \prec \cdots \prec y_k of XX and YY, respectively, such that for i=1,,ki = 1, \dots ,k, B1{x1,,xi}+{y1,,yk}B_1 - \{ x_1, \dots ,x_i\} + \{y_1, \dots ,y_k \} and B2{y1,,yi}+{x1,,xk}B_2 - \{ y_1, \dots ,y_i\} + \{x_1, \dots ,x_k \} are bases; that is, XX is serially exchangeable with YY. Let MM be a rank-nn matroid which is representable over Fq.\mathbb{F}_q. We show that for q>2,q>2, if bases B1B_1 and B2B_2 are chosen randomly amongst all bases of MM, and if a subset XX of size kln(n)k \le \ln(n) is chosen randomly in B1B_1, then with probability tending to one as nn \rightarrow \infty, there exists a subset YB2Y\subset B_2 such that XX is serially exchangeable with Y.Y.

Cite

@article{arxiv.2305.01085,
  title  = {Serial Exchanges in Random Bases},
  author = {Sean McGuinness},
  journal= {arXiv preprint arXiv:2305.01085},
  year   = {2023}
}
R2 v1 2026-06-28T10:22:52.878Z