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- Douglas Bauer, Hajo Broersma, Nathan Kahl, Aurora Morgana, Edward F. Schmeichel, Thomas M. Surowiec
- Discrete Applied Mathematics
- 2007

- Arthur H. Busch, Michael Ferrara, Nathan Kahl
- Discrete Applied Mathematics
- 2007

Let ω0(G) denote the number of odd components of a graph G. The deficiency of G is defined as def (G) = max X⊆V (G) (ω0(G − X) − |X|), and this equals the number of vertices unmatched by any maximum matching of G. A subset X ⊆ V (G) is called a Tutte set (or barrier set) of G if def (G) = ω0(G − X) − |X|, and an extreme set if def (G − X) = def (G) + |X|.… (More)

- Douglas Bauer, Hajo Broersma, Jan van den Heuvel, Nathan Kahl, Edward F. Schmeichel
- Journal of Graph Theory
- 2013

We study theorems giving sufficient conditions on the vertex degrees of a graph G to guarantee G is t-tough. We first give a best monotone theorem when t ≥ 1, but then show that for any integer k ≥ 1, a best monotone theorem for t = 1 k ≤ 1 requires at least f (k) · |V (G)| nonredundant conditions, where f (k) grows superpolynomially as k → ∞. When t < 1,… (More)

- Daniel Gross, Nathan Kahl, John T. Saccoman
- Discrete Mathematics
- 2010

Recently Alon and Friedland have shown that graphs which are the union of complete regular bipartite graphs have the maximum number of 1-factors over all graphs with the same degree sequence. We identify two families of graphs that have the maximum number of 1-factors over all graphs with the same number of vertices and edges: the almost regular graphs… (More)

- Douglas Bauer, Hajo Broersma, Jan van den Heuvel, Nathan Kahl, Edward F. Schmeichel
- Graphs and Combinatorics
- 2012

We consider sufficient conditions for a degree sequence π to be forcibly k-factor graphical. We note that previous work on degrees and factors has focused primarily on finding conditions for a degree sequence to be potentially k-factor graph-ical. We first give a theorem for π to be forcibly 1-factor graphical and, more generally , forcibly graphical with… (More)

- Douglas Bauer, S. Louis Hakimi, Nathan Kahl, Edward F. Schmeichel
- Networks
- 2009

One of Frank Boesch's best known papers is 'The strongest monotone degree conditions for n-connectedness of a graph' [1]. In this paper, we give a simple sufficient degree condition for a graph to be k-edge-connected, and also give the strongest monotone condition for a graph to be 2-edge-connected.

- Nathan Kahl
- Discrete Applied Mathematics
- 2016

- Jonathan Cutler, Nathan Kahl
- Discrete Mathematics
- 2016

- Douglas Bauer, Hajo Broersma, Jan van den Heuvel, Nathan Kahl, A. Nevo, Edward F. Schmeichel +2 others
- Graphs and Combinatorics
- 2015

- Douglas Bauer, Nathan Kahl, Edward F. Schmeichel, Douglas R. Woodall, M. Yatauro
- Discrete Applied Mathematics
- 2014

Let τ (G) and bind(G) be the toughness and binding number, respectively, of a graph G. Woodall observed in 1973 that τ (G) bind(G) − 1. In this paper we obtain best possible improvements of this inequality except when (1 + √ 5)/2 < bind(G) < 2 and bind(G) has even denominator when expressed in lowest terms.