English

Cameron-Liebler line classes

Combinatorics 2020-07-01 v1

Abstract

New examples of Cameron-Liebler line classes in PG(3,q)\mathrm{PG}(3,q) are given with parameter 12(q21)\frac{1}{2}(q^2 -1). These examples have been constructed for many odd values of qq using a computer search, by forming a union of line orbits from a cyclic collineation group acting on the space. While there are many equivalent characterizations of these objects, perhaps the most significant is that a set of lines L\mathcal{L} in PG(3,q)\mathrm{PG}(3,q) is a Cameron-Liebler line class with parameter xx if and only if every spread S\mathcal{S} of the space shares precisely xx lines with L\mathcal{L}. These objects are related to generalizations of symmetric tactical decompositions of PG(3,q)\mathrm{PG}(3,q), as well as to subgroups of PΓL(4,q)\mathrm{P\Gamma L}(4,q) having equally many orbits on points and lines of PG(3,q)\mathrm{PG}(3,q). Furthermore, in some cases the line classes we construct are related to two-intersection sets in AG(2,q)\mathrm{AG}(2,q). Since there are very few known examples of these sets for qq odd, any new results in this direction are of particular interest.

Keywords

Cite

@article{arxiv.2006.16352,
  title  = {Cameron-Liebler line classes},
  author = {Morgan Rodgers},
  journal= {arXiv preprint arXiv:2006.16352},
  year   = {2020}
}
R2 v1 2026-06-23T16:42:55.864Z