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Constructing trees in graphs with no K2,s
Authors:Suman Balasubramanian  Edward Dobson
Affiliation:Department of Mathematics and Statistics, Mississippi State University, P.O. Drawer MA, Mississippi State, MS 39762
Abstract:Let s ≥ 2 be an integer and k > 12(s ? 1) an integer. We give a necessary and sufficient condition for a graph G containing no K2,s with equation image and equation image to contain every tree T of order k + 1. We then show that every graph G with no K2,s and average degree greater than k ? 1 satisfies this condition, improving a result of Haxell, and verifying a special case of the Erd?s—Sós conjecture, which states that every graph of average degree greater than k ? 1 contains every tree of order k + 1. © 2007 Wiley Periodicals, Inc. J Graph Theory 56: 301–310, 2007
Keywords:trees  Erdő  s—    s conjecture  K2,s
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