



Cory Palmer University of Montana 

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 ErdősStoneSimonovits 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 ErdősSós 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) 

Monday, 3 February 2014 3:10 p.m. in Math 103 4:00 p.m. Refreshments in Math Lounge 109 

Spring 2014 Colloquia & Events Mathematical Sciences  University of Montana 
