Structure Estimation for Discrete Graphical Models: Generalized Covariance Matrices and Their Inverses
Penn collection
Degree type
Discipline
Subject
Markov random fields
model selection
inverse covariance estimation
high-dimensional statistics
exponential families
Legendre duality
Statistics and Probability
Funder
Grant number
License
Copyright date
Distributor
Related resources
Author
Contributor
Abstract
We investigate the relationship between the structure of a discrete graphical model and the support of the inverse of a generalized covariance matrix. We show that for certain graph structures, the support of the inverse covariance matrix of indicator variables on the vertices of a graph reflects the conditional independence structure of the graph. Our work extends results that have previously been established only in the context of multivariate Gaussian graphical models, thereby addressing an open question about the significance of the inverse covariance matrix of a non-Gaussian distribution. The proof exploits a combination of ideas from the geometry of exponential families, junction tree theory and convex analysis. These population-level results have various consequences for graph selection methods, both known and novel, including a novel method for structure estimation for missing or corrupted observations. We provide nonasymptotic guarantees for such methods and illustrate the sharpness of these predictions via simulations.