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Search Publications by: James Shook (Fed)

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Displaying 1 - 10 of 10

Maximally Edge-Connected Realizations and Kundu's k-factor Theorem

August 3, 2023
James Shook
A simple graph $G$ with edge-connectivity $\lambda(G)$ and minimum degree $\delta(G)$ is maximally edge connected if $\lambda(G)=\delta(G)$. In 1964, given a non-increasing degree sequence $\pi=(d_1},\ldots,d_n})$, Jack Edmonds showed that there is a

A characterization of the Centers of Chordal Graphs

September 30, 2022
James Shook, Bing Wei
A graph is $k$-chordal if it does not have an induced cycle with length greater than $k$. We call a graph chordal if it is $3$-chordal. Let $G$ be a graph. The distance between the vertices $x$ and $y$, denoted by $d_G}(x,y)$, is the length of a shortest

A Taxonomic Approach to Understanding Emerging Blockchain Identity Management Systems

January 14, 2020
Loic D. Lesavre, Priam C. Varin, Peter M. Mell, Michael S. Davidson, James Shook
Identity management systems (IDMSs) are widely used to provision user identities while managing authentication, authorization, and data sharing within organizations and on the web. Traditional identity systems typically suffer from single points of failure

Cryptocurrency Smart Contracts for Distributed Consensus of Public Randomness

October 7, 2017
Peter M. Mell, John M. Kelsey, James Shook
Most modern electronic devices can produce a random number. However, it is dicult to see how a group of mutually distrusting entities can have con dence in any such hardware-produced stream of random numbers, since the producer could control the output to

Measuring and Improving the Effectiveness of Defense-in-Depth Postures

January 26, 2017
Peter M. Mell, James Shook, Richard Harang
Defense-in-depth is an important security architecture principle that has significant application to industrial control systems (ICS), cloud services, storehouses of sensitive data, and many other areas. We claim that an ideal defense-in-depth posture is

New Results on Packing Degree Sequences and the 2-Color Discrete Tomography Problem

October 27, 2015
James Shook, Michael Ferrara, Jennifer Diemunsch, Sogol Jahanbekam
A sequence $\pi=(d_1,\ldots,d_n)$ is graphic if there is a simple graph $G$ with vertex set $\{v_1,\ldots,v_n\}$ such that the degree of $v_i$ is the $i$th entry of $\pi$. We say that graphic sequences $\pi_1=(d_1^{(1)},\ldots,d_n^{(1)})$ and $\pi_2=(d_1^{

Threshold Digraphs

December 5, 2012
Brian D. Cloteaux, Michael D. LaMar, Elizabeth R. Moseman, James Shook
A digraph whose degree sequences have a unique vertex labeled realization is called threshold. In this paper we present several characterizations of threshold digraphs and show them to be equivalent. One of the characterizations is new, and allows for a