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...

We design a representation based on the situation calculus to facilitate development, maintenance and elaboration of very large taxonomies of actions. This representation leads to more compact and modular basic action theories (BATs) for reasoning about actions than currently possible. We compare our representation with Reiter’s BATs and prove that our representation inherits all useful propert...

This article considers defeasible beliefs in dynamic settings. In particular, we examine the belief projection problem: what is believed after performing an action and/or receiving new information? The approach is based on an epistemic variant of Reiter’s situation calculus, where actions not only have physical effects but may also provide new information to the agent. The preferential belief s...

When Lin and Reiter introduced the progression of basic action theories in the situation calculus, they were essentially motivated by long-lived robotic agents functioning over thousands of actions. However, their account does not deal with probabilistic uncertainty about the initial situation nor with effector or sensor noise, as often needed in robotic applications. In this paper, we obtain r...

Fundamental to reasoning about actions and beliefs is the projection problem: to decide what is believed after a sequence of actions is performed. Progression is one widely applied technique to solve this problem. In this paper we propose a novel framework for computing progression in the epistemic situation calculus. In particular, we model an agent’s preferential belief structure using condit...

In 2], Reiter presents a formalism for database updates speciication. He uses the \situation calculus", that is, many-sorted rst-order languages for representing knowledge about dynamically changing worlds that evolve through diierent states when actions are executed. In these worlds, properties of their objects depend on the current state of the world. These properties are called uents and cor...

In this paper we study the ramification problem in the setting of time-owl. Standard solutions from the literature on reasoning about action are inadequate because they rely on the assumption that fluents persist, and actions have effects on the next situation only. In this paper we provide a solution to the ramification problem based on an extension of the situation calculus and the work of Mc...

This paper explores different techniques for explanation within the framework of the situation calculus, using the so-called stolen car problem as its main example. Two approaches to explanation are compared: the deductive approach usually found in the literature, and a less common abductive approach. Both approaches are studied in the context of two different styles of representation.

We propose a theory for describing, reasoning about, and simulating transaction models that relax some of the ACID properties of classical transactions. Such models have been proposed for database applications involving long-lived, endless, and cooperative activities. Our approach appeals to non-Markovian theories, in which one may refer to past states other than the previous one. We illustrate...

Among the most frequent reasoning tasks in the situation calculus are projection queries that query the truth of conditions in a future state of affairs. However, in long running action sequences solving the projection problem is complex. The main contribution of this work is a new technique which allows the length of the action sequences to be reduced by reordering independent actions and remo...