In the framework of Generalized Information Theory of J. Kampé de Fériet, a system of axioms for the conditional information is studied without assuming additivity.
@article{urn:eudml:doc:38836,
title = {Sur les informations conditionnelles sans F-composabilit\'e.},
journal = {Stochastica},
volume = {4},
year = {1980},
pages = {81-88},
zbl = {0444.94005},
mrnumber = {MR0573727},
language = {fr},
url = {http://dml.mathdoc.fr/item/urn:eudml:doc:38836}
}
Valverde, Llorenç. Sur les informations conditionnelles sans F-composabilité.. Stochastica, Tome 4 (1980) pp. 81-88. http://gdmltest.u-ga.fr/item/urn:eudml:doc:38836/