Regular fat linear sets

TL;DR

This paper introduces a new class of linear sets called regular fat linear sets, unifying previous concepts, and explores their properties, equivalence classes, and applications to three-weight rank-metric codes.

Contribution

It defines regular fat linear sets, generalizes existing constructions, and links them to rank-metric codes with new bounds.

Findings

New classes of regular fat linear sets in projective spaces for composite n

Characterization of equivalence classes of these sets

Connection to three-weight rank-metric codes and parameter bounds

Abstract

In this work, we introduce $(r,i)$-regular fat linear sets, which are defined as linear sets containing exactly $r$ points of weight $i$ and all other points of weight one. This notion generalizes and unifies existing constructions; scattered linear sets, clubs, and other previously studied families are special cases. We present new classes of regular fat linear sets in PG$(k-1,q^n)$ for composite $n$ and study their equivalence classes. Finally, we show that regular fat linear sets naturally yield three-weight rank-metric codes, which we use to obtain bounds on their parameters.