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Total Positivity in Markov Structures

Accepted version
Peer-reviewed

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Authors

Fallat, S 
Lauritzen, S 
Sadeghi, K 
Uhler, C 
Wermuth, N 

Abstract

We discuss properties of distributions that are multivariate totally positive of order two (MTP2) related to conditional independence. In particular, we show that any independence model generated by an MTP2 distribution is a compositional semigraphoid which is upward-stable and singleton-transitive. In addition, we prove that any MTP2 distribution satisfying an appropriate support condition is faithful to its concentration graph. Finally, we analyze factorization properties of MTP2 distributions and discuss ways of constructing MTP2 distributions; in particular we give conditions on the log-linear parameters of a discrete distribution which ensure MTP2 and characterize conditional Gaussian distributions which satisfy MTP2.

Description

Keywords

association, concentration graph, conditional Gaussian distribution, faithfulness, graphical models, log-linear interactions, Markov property, positive dependence

Journal Title

Annals of Statistics

Conference Name

Journal ISSN

0090-5364

Volume Title

45

Publisher

Institute of Mathematical Statistics
Sponsorship
SF was supported in part by an NSERC Discovery Research Grant, KS by grant #FA9550-12-1-0392 from the U.S. Air Force Office of Scientic Research (AFOSR) and the Defense Advanced Research Projects Agency (DARPA), CU by the Austrian Science Fund (FWF) Y 903-N35, and PZ by the European Union Seventh Framework Programme PIOF-GA-2011-300975.