English

Hadamard matrices modulo 5

Combinatorics 2013-07-09 v1

Abstract

In this paper we introduce modular symmetric designs and use them to study the existence of Hadamard matrices modulo 5. We prove that there exist 5-modular Hadamard matrices of order n if and only if n != 3, 7 (mod 10) or n != 6, 11. In particular, this solves the 5-modular version of the Hadamard conjecture.

Keywords

Cite

@article{arxiv.1307.1981,
  title  = {Hadamard matrices modulo 5},
  author = {Moon Ho Lee and Ferenc Szöllősi},
  journal= {arXiv preprint arXiv:1307.1981},
  year   = {2013}
}

Comments

7 pages, submitted to JCD

R2 v1 2026-06-22T00:47:13.703Z