Planning under Uncertainty in Dynamic Domains - Carnegie Mellon ...

Chapter 2Related workWork in automatic planning began early in the eld of articial intelligence, with suchprograms as GPS [Newell & Simon 1963] and strips [Fikes & Nilsson 1971]. As wellas introducing new planning algorithms [Chapman 1987; McAllester & Rosenblitt1991], later work considered more general conditions, for example where externalevents could take place during plan execution [Vere 1983], where the domain theoryis incomplete or incorrect [Gil 1992; Wang 1996; Gervasio 1996] or where the agentmust consider the relative quality of alternative plans [Perez 1995].There has been a wide variety ofwork done in the design of systems for planningunder uncertainty. In this chapter I provide a survey of some of this work, point outthe work most closely related to this thesis and show how the thesis contributes tothebodyofwork in this area.2.1 Overview of \classical" planning.Broadly, planning systems aim to construct a pattern of behaviour for a performancesystem to accomplish some given goal in its environment. Most planning systems aregiven a representation for possible actions that can be taken in the environment interms of the conditions required to hold for the action to be taken and the eects onthe environment when the action is taken. Systems referred to as \classical" planningsystems typically make the following additional assumptions: The environment can be represented in a sequence of discrete states, which arerepresented using a logical language. The actions are represented in a language similar to that used by strips [Fikes& Nilsson 1971], in which the action's preconditions form a logical sentence overthe language used to dene states, and the action's eects are represented by aset of terms to be added to or deleted from the terms used to represent a state. The goal is a property of a state, characterised by a logical sentence (ratherthan a property of a sequence of states).9