@article{DBLP:journals/amai/TorreT99,
  abstract = {In this paper we introduce Prohairetic Deontic Logic (PDL), a preference-based dyadic deontic logic. In our preference-based interpretation of obligations `A should be (done) if B is (done)' is true if (1) no `not-A and B' state is as preferable as an `A and B' state and (2) the preferred B states are A states. We show that this representation solves 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 deontic dilemmas inconsistent. },
  author = {Leendert W. N. van der Torre and Yao-Hua Tan},
  bibsource = {DBLP, http://dblp.uni-trier.de},
  ee = {http://dx.doi.org/10.1023/A:1018975332469},
  journal = {Ann. Math. Artif. Intell.},
  number = {1-4},
  pages = {49-78},
  title = {Contrary-to-duty reasoning with preference-based dyadic obligations},
  url = {http://icr.uni.lu/leonvandertorre/papers/amai99.pdf},
  volume = {27},
  year = {1999},
  bdsk-url-1 = {http://icr.uni.lu/leonvandertorre/papers/amai99.pdf}
}