English

Comparative monotonicity of linear codes by Hermitian and symplectic hull dimensions

Combinatorics 2026-05-29 v1

Abstract

Extending recent work on the Euclidean hull, we derive closed-form ratio decompositions for the number of linear codes with prescribed Hermitian and symplectic hull dimension. The Hermitian ratio admits a uniform lower bound of at least 2/32/3, while the symplectic ratio decays to 1/q21/q^2 asymptotically; a comparative analysis traces this qualitative difference to the Witt classification of the corresponding classical groups. The results translate directly into monotonicity statements for the number of entanglement-assisted quantum codes obtainable from Hermitian-hull-graded [n,k]q2[n, k]_{q^2} and symplectic-hull-graded [2n,k]q[2n, k]_q classical codes via the Guenda-Jitman-Gulliver and Wilde-Brun constructions, respectively.

Keywords

Cite

@article{arxiv.2605.29204,
  title  = {Comparative monotonicity of linear codes by Hermitian and symplectic hull dimensions},
  author = {Keita Ishizuka},
  journal= {arXiv preprint arXiv:2605.29204},
  year   = {2026}
}