English

On the Largest intersecting set in $GL_2(q)$ and some of its subgroups

Combinatorics 2022-01-05 v3

Abstract

Let qq be a power of a prime number and VV be the 22-dimensional column vector space over a finite field Fq\mathbb{F}_{q}. Assume that SL2(V)<GGL2(V)SL_2(V)<G\leq GL_2(V). In this paper we prove an Erd{\H{o}}s-Ko-Rado theorem for intersecting sets of G and we show that every maximum intersecting set of GG is either a coset of the stabilizer of a point or a coset of Gw\mathcal{G}_{\langle w\rangle}, where Gw={MG:vV,Mvvw}\mathcal{G}_{\langle w\rangle}=\{M\in G:\forall v\in V, Mv-v\in \langle w\rangle\}, for some wV{0}w\in V\setminus \{0\}. It is also shown that every intersecting set of GG is contained in a maximum intersecting set.

Keywords

Cite

@article{arxiv.2110.09055,
  title  = {On the Largest intersecting set in $GL_2(q)$ and some of its subgroups},
  author = {Milad Ahanjideh},
  journal= {arXiv preprint arXiv:2110.09055},
  year   = {2022}
}

Comments

The title has been changed. Also, some parts of the paper were reorganized. Accepted for publication in Comptes Rendus Mathematique