Department of Mathematics,
University of California San Diego
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Math 269 - Combinatorics
Choong-Bum Lee
UCLA
Large and judicious bisections of graphs
Abstract:
It is very well known that every graph on $n$ vertices and $m$ edges admits a bipartition of size at least $m/2$. This bound can be improved to $m/2 + (n-1)/4$ for connected graphs, and $m/2 + n/6$ for graphs without isolated vertices, as proved by Edwards, and Erd\H{o}s, Gy\'arf\'as, and Kohayakawa, respectively. A bisection of a graph is a bipartition in which the size of the two parts differ by at most 1. We prove that graphs with maximum degree $o(n)$ in fact contain a bisection which asymptotically achieves the above bounds. These results follow from a more general theorem, which can also be used to answer several questions and conjectures of Bollob\'as and Scott on judicious bisections of graphs. Joint work with Po-Shen Loh and Benny Sudakov
June 7, 2011
4:00 PM
AP&M 7321
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