Dynamic logic of preference upgrade
Johan van Benthem, Fenrong Liu

Abstract:
Statements not only update our current knowledge, but also have other
dynamic effects. In particular, suggestions or commands `upgrade' our
preferences by changing the current order among worlds. We present a
complete logic of knowledge update plus preference upgrade that works
with dynamic-epistemic-style reduction axioms. This system can model
changing obligations, conflicting commands, or `regret'. We then show
how to derive reduction axioms from arbitrary definable relation
changes. This style of analysis also has a product update version with
preferences between actions, as well as worlds. Some illustrations are
presented involving defaults and obligations. We conclude that our
dynamic framework is viable, while admitting a further extension to
more numerical `utility update'.