Some related phase transitions in phylogenetics and social network analysis

Abstract: Spin systems on trees have found applications ranging from the reconstruction of phylogenies to the analysis of networks with community structure. A key feature of such processes is the interplay between the growth of the tree and the decay of correlations along it. How the resulting threshold phenomena impact estimation depends on the problem considered. I will illustrate this on two recent results: 1) the critical threshold of ancestral sequence reconstruction by maximum parsimony on general phylogenies and 2) the accuracy of estimators based on respondent-driven sampling in hard-to-reach populations.

This is joint work respectively with Jason Wang and Karl Rohe.

Biography: Sebastien Roch is an Associate Professor in the Department of Mathematics at University of Wisconsin-Madison. He earned his Ph.D. in Statistics from the University of California, Berkeley under the guidance of Elchanan Mossel. From 2007-2009, he was a Postdoctoral Researcher at Microsoft Research. From 2009-2012, he was an Assistant Professor in the Department of Mathematics at the University of California-Los Angeles. He was a Kavli Fellow of the National Academy of Sciences in 2014 and he is the recipient of an NSF CAREER Award and of an Alfred P. Sloan Fellowship. His research interests lie at the interface of applied probability, statistics, and theoretical computer science — with an emphasis on biological applications, notably mathematical phylogenetic.

http://www.math.wisc.edu/~roch/