The variation distance closure of an exponential family with a convex set of canonical parameters is described, assuming no regularity conditions. The tools are the concepts of convex core of a measure and extension of an exponential family, introduced previously by the authors, and a new concept of accessible faces of a convex set. Two other closures related to the information divergence are also characterized.
@article{1109868592,
author = {Csisz\'ar, Imre and Mat\'u\v s, Franti\v sek},
title = {Closures of exponential families},
journal = {Ann. Probab.},
volume = {33},
number = {1},
year = {2005},
pages = { 582-600},
language = {en},
url = {http://dml.mathdoc.fr/item/1109868592}
}
Csiszár, Imre; Matúš, František. Closures of exponential families. Ann. Probab., Tome 33 (2005) no. 1, pp. 582-600. http://gdmltest.u-ga.fr/item/1109868592/