This paper examines the semantics of a group of logical techniques, used by the Artificial Intelligence community, and which are fundamental for circumscriptionbased approaches to the situation calculus. At first sight, this calculus appears to be an operationalised version of David Lewis’ account of causal reasoning: there are items – here called ‘situations’ – which are analogous to Lewis’ po...

Robot sensors are usually subject to error. Since in many practical scenarios a probabilistic error model is not available, sensor readings are often dealt with in a hard-coded, heuristic fashion. In this paper, we propose a logic to address the problem from a KR perspective. In this logic the epistemic effect of sensing actions is deferred to so-called fusion actions, which may resolve discrep...

Actions depend crucially on what an agent knows and does not know. For example, an action may have a precondition that requires knowing the referent of a term, which is generally referred to as knowing who or knowing what. Alternatively, executing a sense action may be the result of realizing that the referent of a term is not known yet. The latter requires an agent to reason about all it knows...

In this paper we describe a framework for reasoning about temporal explanation problems, which is based on our previous work on model-based diagnosis of dynamic systems. We use an explicit representation of qualitative temporal information which provides a simpler and more natural representation than the situation calculus. We show how to generate more specific explanations by instantiating exp...

We present a formalization of the blocks world on the basis of the situation calculus and circumscription, and investigate its mathematical properties. The main theorem describes the eeect of the circumscription which solves the frame problem in the presence of ramiications. The theorem is quite general, in the sense that it is applicable not only to the blocks world, but to a whole class of do...

In this paper, to compare the situation calculus and event calculus we formulate both as logic programs and prove properties of these by reasoning with their completions augmented with induction. We thus show that the situation calculus and event calculus imply one another. Whereas our derivation of the event calculus from the situation calculus requires the use of induction, our derivation of ...

We describe a forward reasoning planner for open worlds that uses domain specific information for pruning its search space, as suggested by (Bacchus & Kabanza 1996; 2000). The planner is written in the situation calculus-based programming language GOLOG, and it uses a situation calculus axiomatization of the application domain. Given a sentence to prove, the planner regresses it to an equivalen...

Foot-and-mouth disease (FMD) has increased in significance as a major constraint to international trade in live animals and animal products as the World Trade Organization agreements remove other obstructions. A consequence will be reluctance to immediately declare the presence of FMD if it is thought possible to quickly eliminate its presence and so avoid trade embargoes. This will predispose ...

SOME of the more important indicators of the world social sitm1tion show a solid upward trend since 1050 but, in general, sock1 advance has been nneven in the diffei*eiit coiill,onents of tlerelopmerit, as well as in the cliffereiit countries and the different social groups within countries. In the economically less clereloped regions, progress was l~nrticnl:wly outstanding iii some of the indi...