English

Orthogonal realizations of random sign patterns and other applications of the SIPP

Combinatorics 2022-12-13 v1

Abstract

A sign pattern is an array with entries in {+,,0}\{+,-,0\}. A matrix QQ is row orthogonal if QQT=IQQ^T = I. The Strong Inner Product Property (SIPP), introduced in [B.A.~Curtis and B.L.~Shader, Sign patterns of orthogonal matrices and the strong inner product property, Linear Algebra Appl. 592: 228--259, 2020], is an important tool when determining whether a sign pattern allows row orthogonality because it guarantees there is a nearby matrix with the same property, allowing zero entries to be perturbed to nonzero entries, while preserving the sign of every nonzero entry. This paper uses the SIPP to initiate the study of conditions under which random sign patterns allow row orthogonality with high probability. Building on prior work, 5×n5\times n nowhere zero sign patterns that minimally allow orthogonality are determined. Conditions on zero entries in a sign pattern are established that guarantee any row orthogonal matrix with such a sign pattern has the SIPP.

Keywords

Cite

@article{arxiv.2212.05207,
  title  = {Orthogonal realizations of random sign patterns and other applications of the SIPP},
  author = {Zachary Brennan and Christopher Cox and Bryan A. Curtis and Enrique Gomez-Leos and Kimberly P. Hadaway and Leslie Hogben and Conor Thompson},
  journal= {arXiv preprint arXiv:2212.05207},
  year   = {2022}
}