Showing papers by "Hector J. Levesque published in 2020"
TL;DR: The results allow for both discrete and continuous probability distributions to be used in the specification of beliefs and dynamics, and show how both of these generalize in the presence of degrees of belief, noisy acting and sensing.
8 citations
09 Jul 2020
TL;DR: The same properties as above can be obtained by defining epistemic states as sets of three-valued possible worlds, and are able to shed new light on those properties by recasting them using the more familiar notion of truth over possible worlds.
Abstract: In a recent paper Lakemeyer and Levesque proposed a firstorder logic of limited belief to characterize the beliefs of a knowledge base (KB). Among other things, they show that their model of belief is expressive, eventually complete, and tractable. This means, roughly, that a KB may consist of arbitrary first-order sentences, that any sentence which is logically entailed by the KB is eventually believed, given enough reasoning effort, and that reasoning is tractable under reasonable assumptions. One downside of the proposal is that epistemic states are defined in terms of sets of clauses, possibly containing variables, giving the logic a distinct syntactic flavour compared to the more traditional possible-world semantics found in the literature on epistemic logic. In this paper we show that the same properties as above can be obtained by defining epistemic states as sets of three-valued possible worlds. This way we are able to shed new light on those properties by recasting them using the more familiar notion of truth over possible worlds.
5 citations
09 Jul 2020
TL;DR: A way to conveniently represent domain dynamics in the situation calculus to support belief change in agents, and it is shown how beliefs about domain dynamics can be incorporated into a form of regression rewriting to support reasoning.
Abstract: Agents change their beliefs about the plausibility of various aspects of domain dynamics—effects of physical actions, results of sensing, and action preconditions—as a consequence of their interactions with the world. In this paper we propose a way to conveniently represent domain dynamics in the situation calculus to support such belief change. Furthermore, we suggest patterns to follow when writing the axioms that describe the effects of actions, and prove how these patterns can control the extent to which observations change the agent’s beliefs about action effects. We also discuss the relation of our work to the AGM postulates for belief revision. Finally, we show how beliefs about domain dynamics can be incorporated into a form of regression rewriting to support reasoning.
3 citations