Title: Conditional Rényi entropies from alpha to z and beyond
Abstract: This work in progress is an attempt to bring a little bit
more order into the entropy zoo. We start with the observation that
general alpha-z conditional entropies as defined so far are not closed
under the entropic duality relation which relates conditional
entropies for pure states. We solve this problem by introducing
another parameter and thus a much larger class of conditional
entropies that satisfy data-processing and additivity, and is closed
under duality. We hope that this perspective eventually will lead to
complete characterisations of conditional Rényi entropies and tighter
entropic inequalities, but here I just report on some initial steps.