Turán numbers for forests

Document Type

Presentation Abstract

Presentation Date

2-3-2014

Abstract

The Turán number of a graph H, ex(n,H), is the maximum number of edges in a graph on n vertices which does not contain H as a subgraph. The Erdős-Stone-Simonovits Theorem establishes (essentially) ex(n,H) for graphs H of chromatic number 3 or greater. For bipartite graphs much is still unknown. Of particular interest is the Turán number for trees (this is the Erdős-Sós conjecture). We will concentrate our attention on the Turán number of forests. Bushaw and Kettle determined the Turán number of a forest made up of copies of a path of a fixed length. We generalize their result by finding the Turán number for a forest made of up arbitrary length paths. We also determine the Turán number for a forest made up of arbitrary size stars. In both cases we characterize the extremal graphs.

(joint work with Hong Liu and Bernard Lidický)

Additional Details

Monday, February 3 at 3:10 p.m. in Math 103

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