**Date & Time:** Wednesday, February 03, 2016, 16:00-17:00.

**Venue:** Ramanujan Hall

**Speaker:** Bhalchandra Thatte,

Federal University of Minas Gerais,
Belo Horizonte, Brazil

**Title:** The maximum agreement subtree problem

**Abstract:** I will talk about the following extremal problem on
phylogenetic trees. Let T1 and T2 be two phylogenetic trees both on the
leaf set {1,2,...,n}. It has been conjectured that there exists a subset
X of {1,2,...,n} of cardinality o(log n) such that the restrictions of
T1 and T2 on X are isomorphic. We will show a bound of o(sqrt(log n))
improving on the previously known bound of o(log log n). The talk will
be elementary in nature, and no background of phylogenetic trees or
biology will be necessary. (Joint work with Daniel Martin, Sao Paulo.)