School
of Mathematics and BioSS
Date: Friday 29 January, 15:10pm
Location: JCMB 5323
Speaker:
Professor
David Leslie, Department
of Mathematics and Statistics, University of Lancaster
Title:
Thompson sampling for website optimisation
Abstract:
When
individuals are learning how to behave in an unknown
environment, a statistically sensible thing to do is form
posterior distributions over unknown quantities of
interest (such as features of the environment and
individuals’ preferences) then select an action by
integrating with respect to these posterior distributions.
However reasoning with such distributions is very
troublesome, even in a machine learning context with
extensive computational resources; Savage himself
indicated that Bayesian decision theory is only sensibly
used in reasonably "small" situations.
Random beliefs is a framework in which individuals instead
respond to a single sample from a posterior distribution.
This is a strategy known as Thompson sampling, after its
introduction in a medical trials context by Thompson
(1933), and is used by many Web providers both to select
which adverts to show you and to perform website
optimisation. I will demonstrate that such behaviour
'solves' the exploration-exploitation dilemma in a
contextual bandit setting, which is the framework used by
most current applications. Furthermore I will demonstrate
its usage as a component of a lightweight recommender
system that has recently been deployed at copify.com.
There will be tea and coffee after the seminar in the
Mathematics Common Room (5212).
This seminar is a part of
Maxwell Institute seminar
series.
--
Dr Ioannis Papastathopoulos
Chancellor's Fellow
School of Mathematics
The University of Edinburgh
James Clerk Maxwell Building
Peter Guthrie Tait Road
Edinburgh, EH9 3FD