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» Graphs with Chromatic Roots in the Interval (1, 2)
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59
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COMBINATORICS
2007
42views more  COMBINATORICS 2007»
14 years 10 months ago
Graphs with Chromatic Roots in the Interval (1, 2)
We present an infinite family of 3-connected non-bipartite graphs with chromatic roots in the interval (1, 2) thus resolving a conjecture of Jackson’s in the negative. In addit...
Gordon F. Royle
90
Voted
JCT
2007
94views more  JCT 2007»
14 years 10 months ago
A zero-free interval for flow polynomials of cubic graphs
Let P(G,t) and F(G,t) denote the chromatic and flow polynomials of a graph G. D.R. Woodall has shown that, if G is a plane triangulation, then the only zeros of P(G,t) in (−∞...
Bill Jackson
CPC
2007
88views more  CPC 2007»
14 years 10 months ago
Zero-Free Intervals for Flow Polynomials of Near-Cubic Graphs
Let P(G,t) and F(G,t) denote the chromatic and flow polynomials of a graph G. G.D. Birkhoff and D.C. Lewis showed that, if G is a plane near triangulation, then the only zeros of...
Bill Jackson
GD
2005
Springer
15 years 3 months ago
Bar k-Visibility Graphs: Bounds on the Number of Edges, Chromatic Number, and Thickness
Let S be a set of horizontal line segments, or bars, in the plane. We say that G is a bar visibility graph, and S its bar visibility representation, if there exists a one-to-one co...
Alice M. Dean, William Evans, Ellen Gethner, Joshu...
99
Voted
EJC
2008
14 years 10 months ago
On the adaptable chromatic number of graphs
The adaptable chromatic number of a graph G is the smallest integer k such that for any edge k-colouring of G there exists a vertex kcolouring of G in which the same colour never ...
Pavol Hell, Xuding Zhu