[Colloquium] Talk at TTIC: Mina Karzand, U of W, Madison

[Jerome Allen]

*When:*    Monday, March 9th @ 11:00am

*Where:*   TTIC, 6045 S. Kenwood Avenue, 5th Floor, Room 526



*Who: *     Mina Karzand, U of W, Madison


*Title: *  Focused learning in Graphical models

*Abstract:*  When there is insufficient data to learn a globally accurate
model, successful learning can still be possible if we take into account
the particular task for which the learned model will be employed. Learning
a possibly incorrect or incomplete model, which performs well in the
subsequent prediction (classification or decision making) tasks requires
far fewer training examples than learning a complete model. My work
instantiates this aspiration in several rich and complex data-driven
systems including learning graphical models, online collaborative
filtering, and active learning. In this talk, I dive into the problem of
learning graphical models with this framework in mind.

In the first half of the talk, I look into learning tree-structured Ising
models in which the learned model is used subsequently for prediction based
on partial observations (given the realization of a subset of variables,
predict the value of the remaining ones). The vast majority of previous
work on learning graphical models aims to correctly recover the underlying
graph structure (an impossible task in the data-constrained regime). I show
that it is possible to efficiently learn a tree model that gives accurate
predictions even when there is insufficient data to learn the correct
structure.

The second half of the talk is about speciation rate estimation in
phylogenetic trees. This problem is essentially one of inferring features
of the model (in this case, the speciation or extinction rate) from partial
observations (the sequences at the leaves of the tree) of a latent tree
model (phylogeny). I show that an incomplete and partially incorrect
summary of the tree structure is enough to estimate the speciation rate
with the minimax optimal dependence on the length of observed DNA sequences.


*Jerome Allen*
Executive Assistant to the President
*Toyota Technological Institute*
6045 S. Kenwood Avenue
Room 518
Chicago, IL  60637
p:(773) 702-2311
*jallen at ttic.edu <jallen at ttic.edu>*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.cs.uchicago.edu/pipermail/colloquium/attachments/20200308/bcd3ef26/attachment.html>