@InCollection{Torre99AnUpdateSemantics,
  Title                    = {An update semantics for deontic reasoning},
  Author                   = {van der Torre, L. and Tan, Y>},
  Booktitle                = {Norms, Logics and Information Systems. New Studies on Deontic Logic and Computer Science, Volume 49 in Frontiers in Artificial Intelligence and Applications},
  Publisher                = {IOS Press},
  Year                     = {1999},
  Editor                   = {McNamara, P. and Prakken, H.},
  Pages                    = {73-90},

  Abstract                 = {In this paper we propose the deontic logic DUS, that formalizes reasoning
about prescriptive obligations in update semantics. In DUS the definition of
logical validity of obligations is not based on truth values but on action
dynamics. You know the meaning of a normative sentence if you know the
change it brings about in the ideality relation of anyone the news conveyed
by the norm applies to. },
  Url                      = {http://icr.uni.lu/leonvandertorre/papers/deon98full.ps.Z}
}