English

Renitent lines

Combinatorics 2023-09-11 v2

Abstract

There are many examples for point sets in finite geometry, which behave "almost regularly" in some (well-defined) sense, for instance they have "almost regular" line-intersection numbers. In this paper we investigate point sets of a desarguesian affine plane, for which there exist some (sometimes: many) parallel classes of lines, such that almost all lines of one parallel class intersect our set in the same number of points (possibly mod pp, the characteristic). The lines with exceptional intersection numbers are called renitent, and we prove results on the (regular) behaviour of these renitent lines.

Keywords

Cite

@article{arxiv.2102.11790,
  title  = {Renitent lines},
  author = {Bence Csajbók and Peter Sziklai and Zsuzsa Weiner},
  journal= {arXiv preprint arXiv:2102.11790},
  year   = {2023}
}

Comments

The sharpness of some statements has been proved. There are some new examples and a new section about some dual statements and their consequences regarding the geometric properties of codewords of the $\mathbb{F}_p$-linear code generated by characteristic vectors of lines of $\mathrm{PG}(2,q)$. The latter result generalise an old result of Blokhuis, Brouwer and Wilbrink

R2 v1 2026-06-23T23:26:40.925Z