@INPROCEEDINGS{SchmidtTishkovsky02c, 
AUTHOR = {Schmidt, R. A. and Tishkovsky, D.},
YEAR = {2002}, 
TITLE = {Multi-Agent Logic of Dynamic Belief and Knowledge},
EDITOR = {Flesca, S. and Greco, S. and Leone, N. and Ianni, G.}, 
BOOKTITLE = {Proceedings of the 8th European Conference on Logics in Artificial Intelligence (JELIA)},
SERIES = {Lecture Notes in Artificial Intelligence},
VOLUME = {2424},
PUBLISHER = {Springer},
PAGES = {38--49}
URL = {http://www.cs.man.ac.uk/~schmidt/publications/SchmidtTishkovsky02c.html},
ABSTRACT = {This paper proposes a family of logics for reasoning about the
dynamic activities and informational attitudes, i.e.\ the beliefs
and knowledge, of agents.
The logics are based
on a new formalisations and semantics
of the test operator of 
propositional dynamic logic 
and a representation of actions which
distinguishes abstract actions from concrete actions.
The new test operator, called informational test,
can be used to formalise the beliefs and knowledge of particular agents
as dynamic modalities.
This approach is consistent
with the formalisation
of the agents' beliefs and knowledge
as K(D)45 and S5 modalities.
Properties concerning the preservation of informativeness,
truthfulness and belief 
are proved for a derivative of the informational test operator.
It is shown that common belief and common knowledge
can be expressed in these logics.
As a consequence, 
these logics are more expressive
than propositional dynamic logic with
an extra modality for belief or knowledge.
However, the logics are still decidable and in 2EXPTIME.
Versions of the considered logics express natural additional properties
of beliefs or knowledge and interaction of beliefs or knowledge with
actions.
A simulation of PDL is constructed in one of these extensions.
}
}