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Full-Text Articles in Mathematics

Cyclic Matching Sequencibility Of Graphs, Richard A. Brualdi, Kathleen P. Kiernan, Seth A. Meyer, Michael W. Schroeder Jun 2012

Cyclic Matching Sequencibility Of Graphs, Richard A. Brualdi, Kathleen P. Kiernan, Seth A. Meyer, Michael W. Schroeder

Mathematics Faculty Research

We define the cyclic matching sequencibility of a graph to be the largest integer d such that there exists a cyclic ordering of its edges so that every d consecutive edges in the cyclic ordering form a matching. We show that the cyclic matching sequencibility of K2m and K2m+1 equals m − 1.


Extremal Problems For Roman Domination, E. W. Chambers, W. Kinnersley, N. Prince, D. B. West Apr 2012

Extremal Problems For Roman Domination, E. W. Chambers, W. Kinnersley, N. Prince, D. B. West

Noah Prince

A Roman dominating function of a graph G is a labeling f: V(G) →{0,1,2} such that every vertex with a label 0 has a neighbor with label 2. The Roman domination number γR(G) of G is the minimum of ∑ʋϵV(G)f(v) over such functions. Let G be a connected n-vertex graph. We prove that γR(G) ≤ 4n/5, and we characterize the graphs achieving equality. We obtain sharp upper and lower bounds for γR(G) + …


Highly Connected Monochromatic Subgraphs Of Multicoloured Graphs, H. Liu, R. Morris, N. Prince Apr 2012

Highly Connected Monochromatic Subgraphs Of Multicoloured Graphs, H. Liu, R. Morris, N. Prince

Noah Prince

We consider the following question of Bollobás: given an r-coloring of E(Kn), how large a k-connected subgraph can we find using at most s colors? We provide a partial solution to this problem when s=1 (and n is not too small), showing that when r=2 the answer is n−2k+2, when r=3 the answer is ⌊(n−k)/2⌋+1 or ⌈(n−k)/2⌉+1, and when r−1 is a prime power then the answer lies between n/(r−1)−11(k2−k)r and (n−k+1)/(r−1)+r. The case s≥2 is considered in a subsequent paper (Liu et al.[6]), where we also discuss some of the more glaring open problems relating to this question.


Dihedral Cayley Directed Strongly Regular Graphs, Jose Jonathan Gamez Jan 2012

Dihedral Cayley Directed Strongly Regular Graphs, Jose Jonathan Gamez

Open Access Theses & Dissertations

A graph is a directed strongly regular graph (DSRG) if and only if the number of paths of length 2 from x to y is: λ, if there is an edge from x to y; μ, if there is not an edge from x to y (with x not equal to y); and t, if x = y. For every vertex in G, the in-degree and out-degree is k. The number of vertices in G is denoted by v. If G is a group and S a subset of G, then the …