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20172025
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math.CO2025

Counting Cholesky factorizations of the zero matrix over

Joshua Cooper, Hays Whitlatch

A square, upper-triangular matrix is a Cholesky root of a matrix provided , where represents the conjugate transpose when working over the complex field a…

math.CO2024

Characterization of Trees with Maximum Security

Alex S. A. Alochukwu, Audace A. V. Dossou-Olory, Fadekemi J. Osaye +5

The rank (also known as protection number or leaf-height) of a vertex in a rooted tree is the minimum distance between the vertex and any of its leaf descendants. We consider the s…

math.CO2022

Positive-Definite Matrices over Finite Fields

Joshua Cooper, Erin Hanna, Hays Whitlatch

The study of positive-definite matrices has focused on Hermitian matrices, that is, square matrices with complex (or real) entries that are equal to their own conjugate transposes.…

math.CO2022

Counting Power Domination Sets in Complete m-ary Trees

Sviatlana Kniahnitskaya, Michele Ortiz, Olivia Ramirez +2

Motivated by the question of computing the probability of successful power domination by placing k monitors uniformly at random, in this paper we give a recursive formula to count…

math.CO2018

A New Characterization of -Posets

Joshua Cooper, Peter Gartland, Hays Whitlatch

In 2016, Hasebe and Tsujie gave a recursive characterization of the set of induced -free and bowtie-free posets; Misanantenaina and Wagner studied these orders further, naming t…

math.CO2017

Analogies between the crossing number and the tangle crossing number

Robin Anderson, Shuliang Bai, Fidel Barrera-Cruz +8

Tanglegrams are special graphs that consist of a pair of rooted binary trees with the same number of leaves, and a perfect matching between the two leaf-sets. These objects are of…