Discussiones Mathematicae Graph Theory 33(4) (2013) 771-784
doi: 10.7151/dmgt.1710

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Almost-rainbow Edge-colorings of Some Small Subgraphs

Elliot Krop

Department of Mathematics, Clayton State University
2000 Clayton State Boulevard, Morrow, GA 30260 USA

Irina Krop

DePaul University
1 E. Jackson, Chicago, IL 60604 USA

Abstract

Let f(n,p,q) be the minimum number of colors necessary to color the edges of Kn so that every Kp is at least q-colored. We improve current bounds on these nearly "anti-Ramsey" numbers, first studied by Erdös and Gyárfás. We show that f(n,5,9) ≥ 7/4(n-3), slightly improving the bound of Axenovich. We make small improvements on bounds of Erdös and Gyárfás by showing 5/6(n+1)≤ f(n,4,5) and for all even n≢ 1(mod 3), f(n,4,5)≤ n-1. For a complete bipartite graph G=Kn,n, we show an n-color construction to color the edges of G so that every C4⊆ G is colored by at least three colors. This improves the best known upper bound of Axenovich, Füredi, and Mubayi.

Keywords: Ramsey theory, generalized Ramsey theory, rainbow-coloring, edge-coloring, Erdös problem

2010 Mathematics Subject Classification: 05A15, 05C38, 05C55.

References

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Received 6 December 2012
Revised 21 September 2012
Accepted 21 September 2012