This paper proposes a new logic programming language called GOLOG whose interpreter automatically maintains an explicit representation of the dynamic world being modeled, on the basis of user supplied axioms about the preconditions and effects of actions and the initial state of the world. This allows programs to reason about the state of the world and consider the effects of various possible courses of action before committing to a particular behavior. The net effect is that programs may be written at a much higher level of abstraction than is usually possible. The language appears well suited for applications in high level control of robots and industrial processes, intelligent software agents, discrete event simulation, etc. It is based on a formal theory of action specified in an extended version of the situation calculus. A prototype implementation in Prolog has been developed.

A class of interval-based temporal languages for uniformly representing and reasoning about actions and plans is presented. Actions are represented by describing what is true while the action itself is occurring, and plans are constructed by temporally relating actions and world states. The temporal languages are members of the family of Description Logics, which are characterized by high expressivity combined with good computational properties. The subsumption problem for a class of temporal Description Logics is investigated and sound and complete decision procedures are given. The basic language TL-F is considered #rst: it is the composition of a temporal logic TL # able to express interval temporal networks # together with the non-temporal logic F # a Feature Description Logic. It is proven that subsumption in this language is an NP-complete problem. Then it is shown how to reason with the more expressive languages TLU-FU and TL-ALCF . The former adds disjunction both at...

this paper, we survey a wide range of research in temporal representation and reasoning, without committing ourselves to the point of view of any speci c application

Abstract Our focus in this paper is on natural exogenous actions (Pinto [8]), namely those which occur in response to known laws of physics, like a ball bouncing at times determined by Newtonian equations of motion. The property of such actions that we wish to capture is that they must occur at their predicted times, provided no earlier actions (natural or agent initiated) prevent them from occurring. Because several such actions may occur simultaneously, we need a theory of concurrency. Because such actions may be modeled by equations of motion, we need to represent continuous time. This paper shows how to gracefully accommodate all these features within the situation calculus, without sacrificing the simple solution to the frame problem of Reiter [9]. The end result is a situation calculus account of deductive planning, with continuous time and true concurrency, and where the agent can incorporate external natural event occurrences into her plans. 1 Formal Preliminaries 1.1 The Lan...

A temporal logic for representing and reasoning on a robotic domain is presented. Actions

The area of reasoning about action and change is concerned with the formalization of actions and their e ects as well as other aspects of inhabited dynamical systems. The representation is typically done in some logical language. Although there has been substantial progress recently regarding the frame problem and the rami cation problem, many problems still remain. One of these problems is the representation of concurrent actions and their e ects. In particular, the e ects of two or more actions executed concurrently may be di erent from the union of the e ects of the individual actions had they been executed in isolation. This thesis presents a language, tal-c, which supports detailed and exible yet modular descriptions of concurrent interactions. Two related topics, which both require a solution to the concurrency problem, are also addressed: the representation of e ects of actions that occur with some delay, and the representation of actions that are caused by other actions. Another aspect of reasoning about action and change is how to describe