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On Hadwiger's number— a problem of the Nordhaus-Gaddum type

✍ Scribed by M. Stiebitz


Publisher
Elsevier Science
Year
1992
Tongue
English
Weight
700 KB
Volume
101
Category
Article
ISSN
0012-365X

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✦ Synopsis


Stiebitz, M., On Hadwiger's number-A problem of the Nordhaus-Gaddum type, Discrete Mathematics 101 (1992) 307-317. The Hadwiger number of a graph G = (V, E), denoted by q(G), is the maximum size of a complete graph to which G can be contracted. Let %((n, k):= {G 1 IV(G)1 = n and n(G) = k}. We shall investigate F(n, k) := max{n(G) 1 GE %((n, k)} and f(n, k):= min{q(G) 1 G E %(n, k)}. Problems of this type were first considered by Nordhaus and Gaddum (1956) for the chromatic number. The main results are contained in Theorem 1.4 and Theorem 1.6.


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