Monthly Archives: March 2016

Multitask matrix completion for learning protein interactions across diseases

Four our next meeting on 3/28/2016 we have selected Multitask matrix completion for learning protein interactions across diseases by Kshirsagar et al. The abstract is as follows.

Disease causing pathogens such as viruses, introduce their proteins into the host cells where they interact with the host’s proteins enabling the virus to replicate inside the host. These interactions be- tween pathogen and host proteins are key to understanding infectious diseases. Often multiple diseases involve phylogenetically related or bio- logically similar pathogens. Here we present a multitask learning method to jointly model interactions between human proteins and three different, but related viruses: Hepatitis C, Ebola virus and Influenza A. Our multi- task matrix completion based model uses a shared low-rank structure in addition to a task-specific sparse structure to incorporate the various in- teractions. We obtain upto a 39% improvement in predictive performance over prior state-of-the-art models. We show how our model’s parame- ters can be interpreted to reveal both general and specific interaction- relevant characteristics of the viruses. Our code and data is available at:

We look forward to seeing all who can come. Feel free to begin our discussion in the comments section below.

Factor graphs and the sum-product algorithm

Dear Journal Club members,

Our next meeting will be on March 14th, at noon in room 3160 of the Discovery Building. For this meeting we have selected the a paper by Kschischang et al, Factor graphs and the sum-product algorithm from IEEE. The abstract is presented below.

Algorithms that must deal with complicated global functions of many variables often exploit the manner in which the given functions factor as a product of “local” functions, each of which depends on a subset of the variables. Such a factorization can be visualized with a bipartite graph that we call a factor graph, In this tutorial paper, we present a generic message-passing algorithm, the sum-product algorithm, that operates in a factor graph. Following a single, simple computational rule, the sum-product algorithm computes-either exactly or approximately-various marginal functions derived from the global function. A wide variety of algorithms developed in artificial intelligence, signal processing, and digital communications can be derived as specific instances of the sum-product algorithm, including the forward/backward algorithm, the Viterbi algorithm, the iterative “turbo” decoding algorithm, Pearl’s (1988) belief propagation algorithm for Bayesian networks, the Kalman filter, and certain fast Fourier transform (FFT) algorithms

Please feel free to start the discussion in the comments section below.