Nils Bulling, Computational Intelligence Group, Clausthal University of Technology

**Abstract:**

Logics of knowledge and belief are often too static and inflexible
to be used on real-world problems. In particular, they
usually offer no concept for expressing that some course of
events is more likely to happen than another. We address
this problem and extend CTLK (computation tree logic
with knowledge) with a notion of plausibility, which allows
for practical and counterfactual reasoning. The new logic
CTLKP (CTLK with plausibility) includes also a particular
notion of belief. A plausibility update operator is added
to this logic in order to change plausibility assumptions dynamically.
Furthermore, we examine some important properties
of these concepts. In particular, we show that, for a
natural class of models, belief is a KD45 modality. We also
show that model checking CTLKP is PTIME-complete
and can be done in time linear with respect to the size of
models and formulae.

**Keywords:** multi-agent systems, temporal logic, plausibility, beliefs.

Computational Intelligence Group @ Technical University of Clausthal | |

Human Media Interaction Group @ University of Twente | |

Computer Science Group @ University of Gdansk | Last modified 2007-05-22 |