Speaker Anima Anandkumar
Affiliation UC Irvine
Host Nancy Baym
Date recorded 14 May 2014
In any learning task, it is natural to incorporate latent or hidden variables which are not directly observed. For instance, in a social network, we can observe interactions among the actors, but not their hidden interests/intents, in gene networks, we can measure gene expression levels but not the detailed regulatory mechanisms, and so on. I will present a broad framework for unsupervised learning of latent variable models, addressing both statistical and computational concerns. We show that higher order relationships among observed variables have a low rank representation under natural statistical constraints such as conditional-independence relationships. We also present efficient computational methods for finding these low rank representations. These findings have implications in a number of settings such as finding hidden communities in networks, discovering topics in text documents and learning about gene regulation in computational biology. I will also present principled approaches for learning overcomplete models, where the latent dimensionality can be much larger than the observed dimensionality, under natural sparsity constraints. This has implications in a number of applications such as sparse coding and feature learning.
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