@INPROCEEDINGS{hu-noAI93,
AUTHOR = {Ullrich Hustadt and Andreas Nonnengart},
TITLE = {Modalities in Knowledge Representation},
BOOKTITLE = {Proceedings of the 6th Australien Joint Conference on Artificial Intelligence (AI '93)},
EDITOR = {Chris Rowles and Huan Liu and Norman Foo},
PAGES = {249--254},
PUBLISHER = {World Scientific},
YEAR = {1993},
ABSTRACT = {Standard knowledge representation systems are 
supposed to be able to represent either common or individual 
knowledge about the world. In this paper we propose an 
extension to such knowledge representation systems which, in 
a uniform manner, allows to express beliefs of multiple agents 
as well as knowledge, desire, time and in fact any modality 
which has a first-order predicate logic possible world semantics.},
}