Delsarte duality on subspaces and applications to rank-metric codes and q-matroids

Fuente: arXiv
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Autores principales: Borello, Martino, Polverino, Olga, Zullo, Ferdinando
Formato: Preprint
Publicado: 2025
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author Borello, Martino
Polverino, Olga
Zullo, Ferdinando
author_facet Borello, Martino
Polverino, Olga
Zullo, Ferdinando
contents We study the interplay between the lattice of F_{q^m}-subspaces and the lattice of F_{q^m}-subspaces of an F_{q^m}-vector space. Introducing notions of weight and defect relative to an F_q-subspace, we analyze the sequence of maximum non-zero defects. We establish a correspondence between subspaces of positive defect and their Delsarte duals, enabling explicit characterizations of the associated sequences of maximum non-zero defects. Our framework unifies several classes of subspaces studied in finite geometry and connects them to linear rank-metric codes by providing a new geometric interpretation of code duality. Building on these results, we characterize classes of rank-metric codes closed under duality, including MRD, near MRD, quasi-MRD, and a new family of (n, k)-MRD codes. Finally, we explore applications to q-matroids, by studying the problem of F_{q^m}-representability for direct sums of uniform q-matroids and describing their rank generating functions.
format Preprint
id arxiv_https___arxiv_org_abs_2509_24409
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Delsarte duality on subspaces and applications to rank-metric codes and q-matroids
Borello, Martino
Polverino, Olga
Zullo, Ferdinando
Combinatorics
Information Theory
We study the interplay between the lattice of F_{q^m}-subspaces and the lattice of F_{q^m}-subspaces of an F_{q^m}-vector space. Introducing notions of weight and defect relative to an F_q-subspace, we analyze the sequence of maximum non-zero defects. We establish a correspondence between subspaces of positive defect and their Delsarte duals, enabling explicit characterizations of the associated sequences of maximum non-zero defects. Our framework unifies several classes of subspaces studied in finite geometry and connects them to linear rank-metric codes by providing a new geometric interpretation of code duality. Building on these results, we characterize classes of rank-metric codes closed under duality, including MRD, near MRD, quasi-MRD, and a new family of (n, k)-MRD codes. Finally, we explore applications to q-matroids, by studying the problem of F_{q^m}-representability for direct sums of uniform q-matroids and describing their rank generating functions.
title Delsarte duality on subspaces and applications to rank-metric codes and q-matroids
topic Combinatorics
Information Theory
url https://arxiv.org/abs/2509.24409