@inproceedings{Torre98ProhaireticDeontic,
  abstract = {In this paper we introduce Prohairetic Deontic Logic (PDL), a preference-based dyadic deontic logic. An obligation ‘α should be (done) if β is (done)’ is true if (1) no ¬α∧β state is as preferable as an α∧β state and (2) the preferred β states are α states. We show that the different elements of this mixed representation solve different problems of deontic logic. The first part of the definition is used to formalize contrary-to-duty reasoning, that for example occurs in Chisholm’s and Forrester’s notorious deontic paradoxes. The second part is used to make dilemmas inconsistent. PDL shares the intuitive semantics of preference-based deontic logics without introducing additional semantic machinery such as bi-ordering semantics or ceteris paribus preferences. },
  author = {van der Torre, L. and Tan, Y.},
  booktitle = {Logics in Artificial Intelligence. Proceedings of the 6th European Workshop on Logics in AI (JELIA'98)},
  pages = {77-91},
  publisher = {Springer},
  series = {LNAI},
  title = {Prohairetic Deontic Logic (PDL)},
  volume = {1489},
  url = {http://www.springerlink.com/content/gwactbelcpx3y2rc},
  year = {1998}
}