Seminar Announcement** * ------------------------------------------------------------------------ * *Coalescence in branching processes* **** *Krishna Athreya* ***Department of Statistics* *Iowa State University* *_Johnson Center G19 - Gold Room _* *_4400 University Drive, Fairfax, VA 22030_*__ *_Time: 11:00 A.M. - 12:00 P.M._*__ *_Date: Friday, Sep 14, 2012 _*__ *Abstract* Consider a branching tree. Go to the nth generation. If there are at least two vertices in that generation pick two of them at random by srswor (simple random sampling without replacement) and trace their lines of descent back in time till they meet. Call that generaion Xn. Do the same thing with all individuals in the nth generation. Call that Yn. In this talk we discuss the distributions of Xn and Yn and their asymptotics for Galton Watson trees as n goes to infinity for single and multitype cases for the four cases: subcritical, critical, supercritical, explosive.Applications to branching random walks will also be discussed. -- Yunpeng Zhao, PhD Assistant Professor Department of Statistics Volgenau School of Engineering<mailto:[log in to unmask]> George Mason University Engineering Building, Room 1719, MS 4A7 4400 University Drive Fairfax, VA 22030-4444 Phone: 703-993-1674 Email: [log in to unmask] <mailto:[log in to unmask]>