Displaying similar documents to “Class reconstruction numbers of unicyclic graphs”

Complete minors, independent sets, and chordal graphs

József Balogh, John Lenz, Hehui Wu (2011)

Discussiones Mathematicae Graph Theory

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The Hadwiger number h(G) of a graph G is the maximum size of a complete minor of G. Hadwiger's Conjecture states that h(G) ≥ χ(G). Since χ(G) α(G) ≥ |V(G)|, Hadwiger's Conjecture implies that α(G) h(G) ≥ |V(G)|. We show that (2α(G) - ⌈log_{τ}(τα(G)/2)⌉) h(G) ≥ |V(G)| where τ ≍ 6.83. For graphs with α(G) ≥ 14, this improves on a recent result of Kawarabayashi and Song who showed (2α(G) - 2) h(G) ≥ |V(G) | when α(G) ≥ 3.

The chromaticity of a family of 2-connected 3-chromatic graphs with five triangles and cyclomatic number six

Halina Bielak (1998)

Discussiones Mathematicae Graph Theory

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In this note, all chromatic equivalence classes for 2-connected 3-chromatic graphs with five triangles and cyclomatic number six are described. New families of chromatically unique graphs of order n are presented for each n ≥ 8. This is a generalization of a result stated in [5]. Moreover, a proof for the conjecture posed in [5] is given.