BEGIN:VCALENDAR
VERSION:2.0
PRODID:talks.ox.ac.uk
BEGIN:VEVENT
SUMMARY:Orderings of Gibbs random samples - Yuri Yakubovich (St Petersburg
State University)
DTSTART;VALUE=DATE-TIME:20190121T120000Z
DTEND;VALUE=DATE-TIME:20190121T130000Z
UID:https://talks.ox.ac.uk/talks/id/3caadf9c-f9b7-43b3-9f75-18c738f6423e/
DESCRIPTION:Random partitions of finite sets play a key role in modelling
genetic diversity. The basic problem is to draw statistical inference abo
ut the general population where a sample partition on species is only obse
rvable. Mathematical models are greatly simplified by assuming that the po
pulation itself is a sample from an idealized infinite population\, due to
Kingman’s theory of exchangeable random partitions of countable sets\,
whereby partitions are modelled by sampling from a random discrete distrib
ution. In population genetics\, the sample values may carry additional cha
racteristics of the species. For example\, in Moran’s model with infinit
ely many alleles\, such a characteristic encodes the relative age of speci
es\, and the question of interest is\, given the observed frequencies of s
pecies in the sample\, to order them by age. Donnelly & Tavaré (1986) pro
ved that in the GEM(θ) model (which leads to the famous Ewens sampling fo
rmula)\, the distribution of the order by age is the same as that of the o
rder by appearance. In my talk\, I will show that in a two-parametric gene
ralization of the GEM model\, and more generally\, under the so-called Gib
bs sampling\, these two orders have different distributions which are neve
rtheless connected via a modification of the stochastic procedure known as
size-biased ordering.\nThis is joint work with Jim Pitman (Berkeley)\, do
i:10.1214/17-EJP59\; doi:10.1214/17-ECP95.\nSpeakers:\nYuri Yakubovich (St
Petersburg State University)
LOCATION:Mathematical Institute\, Woodstock Road OX2 6GG
TZID:Europe/London
URL:https://talks.ox.ac.uk/talks/id/3caadf9c-f9b7-43b3-9f75-18c738f6423e/
BEGIN:VALARM
ACTION:display
DESCRIPTION:Talk:Orderings of Gibbs random samples - Yuri Yakubovich (St P
etersburg State University)
TRIGGER:-PT1H
END:VALARM
END:VEVENT
END:VCALENDAR