Xavier Parent, "Preference-based semantics for dyadic deontic logics
in Hansson's tradition: a survey of axiomatisation results".

Abstract ======== I present and discuss a number of axiomatization
results about so-called dyadic deontic logics in the preference-based
semantics tradition.  These rely on ranking possible worlds in terms
of an Hanssonian binary preference relation of comparative goodness or
betterness.  In that framework the conditional obligation operator is
defined in terms of best antecedent-worlds.  The goal is to identify
the different systems that can be obtained, depending on the special
properties envisaged for the betterness relation, and depending on how
the notion of ''best" is understood (optimality vs.  maximality,
stringent vs. liberal maximization).  If time allows, decidability
issues will also be discussed.

The material presented in this talk is based on an overview chapter in
preparation commissioned for the 2nd volume of the ''Handbook of
Deontic Logic and Normative Systems".