English

Cardinality-consistent flag codes with longer type vectors

Information Theory 2026-01-14 v1 Combinatorics math.IT

Abstract

Flag codes generalize constant dimension codes by considering sequences of nested subspaces with prescribed dimensions as codewords. A comprehensive construction, which unites cyclic orbit flag codes, yields two families of flag codes on Fqn\mathbb{F}^n_q (where n=sk+hn=sk+h with s2s\geq 2 and 0h<k0\leq h < k): optimum distance flag codes of the longest possible type vector (1,2,,k,nk,,n1)(1, 2, \ldots, k, n-k, \ldots, n-1) and flag codes with longer type vectors (1,2,,k+h,2k+h,,(s2)k+h,nk,,n1)(1, 2, \ldots, k+h, 2k+h, \ldots, (s-2)k+h, n-k, \ldots, n-1). These flag codes achieve the same cardinality i=1s1qik+h+1\sum^{s-1}_{i=1}q^{ik+h}+1.

Keywords

Cite

@article{arxiv.2601.08144,
  title  = {Cardinality-consistent flag codes with longer type vectors},
  author = {Junfeng Jia and Yanxun Chang},
  journal= {arXiv preprint arXiv:2601.08144},
  year   = {2026}
}
R2 v1 2026-07-01T09:01:58.546Z