Sacerdoti E. D., A structure for plans and behavior, Elsevier-North Holland, 1977.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Axiom (3) states that the possible worlds consistent with any agent s knowledge is a subset of the possible worlds consistent with the kernel of that agent and any other agent. IH. THE KAMP PLANNING SYSTEM KAMP is a multiple agent planning system designed around a NOAH like hierarchical planner [10]. KAMP uses two descriptions of each action available to the planning agent: a complete axiomatization of the action using the possible worlds approach outlined above, and an action Notice that the intersection of the propositions believed by two agents is represented by the union of possible ....

Sacerdoti, Earl, A Structure for Plans and Behavior, Elsevier North-Holland, Inc., Amsterdam, 1977.

....needs a theoretical perspective for a proper evaluation of the most important planning algorithms. The theory reported in Yang s book gives, in our opinion, this perspective. For instance, we agree with the choice of using the STRIPS representation. This choice is justified by its vast popularity [10,23,24,36,37,39], by its clear and 6 An operator overlapping (delete condition) interaction occurs when an operator relevant for achieving a goal adds (deletes) the precondition of an operator relevant for another goal. 8 well founded semantics [35] and by the fact that most of the more sophisticated ....

.... 8 Conclusions Several areas of Artificial Intelligence have been adequately covered by monographs, e.g. case based reasoning [32] natural language [5] and machine learning [34] Concerning planning, we can find two kinds of books: books whose topic is the presentation of specific systems (e.g. [39,44]) and readings (e.g. 3,4] In both cases there is no effort on providing a general and or theoretical framework of planning. Yang s book fills this gap. It is a comprehensive monograph on classical planning and gives the added value of providing a unified theoretical framework as well as ....

E.D. Sacerdoti. A Structure for Plans and Behaviour. Elsevier-North Holland, 1977.

....is familiar from Prolog like languages, the multiplicative clauses provided by BI have a di#erent interpretation which provides an account of local variables and interference in logic programming. An example will illustrate these ideas. Consider a simple version of the famous blocks world [40], in which a robotic arm is supposed to manipulate blocks, here labelled x, y and z. Suppose further that we wish to remove from the computation imagine perhaps that it is a construction process any components that may be defective. A sketch of a possible program P follows the diagram: x y ....

E. D. Sacerdoti, A structure for plans and behaviour, Elsevier North Holland, 1977.

....incompatible languages. 3.4 Parsers and other PMs There are many alternatives to the one step at a time process of the SMs described above: any notion of planning and problem decomposition can be turned into a PM. Some of the ones we have been considering are abstraction hierarchies [70] 71] [72], case based planning [28] 29] 37] constraint based planners [80] 81] plan reuse [20] mixedinitiative planning [65] agent planning [2] 59] 67] and others [6] 23] 84] The one we describe here is a distributed planning PM called the Horde Planner (HP) The HP tries to collect ....

Earl D. Sacerdoti, A Structure for Plans and Behavior, Elsevier North-Holland (1977)

....defined purpose. This task is represented in MRG by the solve tactics, whose argument is of the type goal. Simple solve tactics are compositions of plan for and exec tactics, where plan formation is followed by plan execution. This is what usually happens in classical planners (as for instance in [17, 23, 24, 25, 3]) For instance: DEFTAC t classic goto (position) t exec nav plan (t plan shortest route position) where t exec nav plan and t plan shortest route are an execution and a plan formation tactic respectively. Note that the two fundamental planning steps, plan formation and plan execution, are ....

E.D. Sacerdoti. A Structure for Plans and Behaviour. Elsevier-North Holland, 1977.

....case, to the full control case. In this paper, we summarize the framework of temporally abstract reinforcement learning and present new theoretical results on planning with general options and temporally abstract models of options. Options are similar to AI s classical macro operators [7, 8, 16], in that they can take control for some period of time, determining the actions during that time, and in that one can choose among options much as one originally chose among primitive actions. However, classical macro operators are only a fixed sequence of actions, whereas options incorporate a ....

Earl D. Sacerdoti. A Structure for Plans and Behavior. Elsevier North-Holland, 1977.

....problem, and search in graph structures. 6 On The Blocks World The blocks world is a formulation of a simple problem in AI, where a robot is allowed to perform a number of primitive actions in a simple world (see for instance [19] Here we consider a simple version of this problem by [20], where there are three blocks, say a, b, c, and three different places of a table, say p, q and r. A block is allowed to lay either above another block or on one of these places. Blocks can be moved from one to another location. A possible initial situation is illustrated in Figure 1. c p r q ....

E.D. Sacerdoti. A Structure for Plans and Behaviour. Elsevier North-Holland, New York, 1977.

....operator system and the linguistic knowledge. 6 The plan operator Each communicative act, including an illocutionary act and locutionary act, or a rhetorical relation is formalized as a plan operator (e.g. Figure 2 shows an example of plan operator) As in traditional planning paradigms (Sacerdoti 77) each plan operator defines the preconditions that must hold before a communicative act can be executed, the constraints on the occurring act, its intended effects, as well as its refinement or decomposition into sub actions. We follow Maybury s plan operator definition (Maybury 92) ....

Earl D. Sacerdoti. A structure for plans and behavior. Elsevier North-Holland, Inc., 1977.

....to the hand movement is X is waving to Y . Most attempts at logical formalization of action and, particularly, the effects of an action or movement in a context, appeared in research in either philosophy and linguistics (e.g. 68, 69, Chapter 1 Introduction 21 138, 149] or formal logic [50, 55, 148]. The linguistic approaches were in general aimed at the processing of natural language and are normally cluttered with semantic problems. Logic approaches have been basically aimed to develop formalisms to infer logical consequences of actions through deep reasoning mechanisms. Logical systems ....

....movements and a recognition mechanism based on Hu moments. 2.2.3 Representing Change and Causality A great deal of work in artificial intelligence has been concerned with how to represent change and causality. Starting with the pioneering work of Nilsson [50] McCarthy [101] and Sacerdoti [148], action representation has gone into increasingly levels of sophistication. A good survey, exploring in detail the temporal structure, is given by Allen and Ferguson in [6] see also [166] More recently there has been much interest in the concept of fluents, particularly in the work of Gelfond ....

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E. D. Sacerdoti. A Structure for Plans and Behavior. Elsevier North-Holland, New York. 1977.

....plans to guide the tutoring agent. To demonstrate tasks, the tutoring agent executed appropriate steps from these plans. To evaluate student performance, the agent used these plans to drive a plan recognition algorithm. The plans were represented using a variant of Sacerdoti s procedural networks [5]. This representation gave course instructors considerable flexibility in describing plans; for example, the plans could contain partially ordered steps, alternatives, and conditional tests. However, the plans had to cover all possible alternatives and contingencies, because the tutoring agent ....

E. Sacerdoti. A Structure for Plans and Behavior. Elsevier North-Holland, New York, 1977.

....Many of the early planners had a different view of planning than how we view planning recently. They viewed planning mainly as a separate entity from execution and assumed there is only one active agent in the world at any time. Some of these earlier classical planners are STRIPS [5, 6] NOAH [13] and SIPE [15] These classical planning approaches will work well when one can assume that the planner has complete knowledge of the current state and the cause andeffect relationships of every action in that world. However, for situations which cannot guarantee the above ideal ....

E.D. Sacerdoti. A Structure for Plans and Behaviour. Elsevier-North Holland, 1977.

....of the National Science Foundation or ONR. example, strips style planning systems 1 were developed more than twenty years ago (Fikes et al. 1971) and most of the practical work on AI planning systems for the last fifteen years has been based on hierarchical task network (htn) decomposition (Sacerdoti, 1977; Tate, 1990; Wilkins, 1988a; Wilkins, 1988b) In contrast, although the past few years have seen much analysis of planning using strips style operators, Chapman, 1987; Mcallester et al. 1991; Erol et al. 1992b; Erol et al. 1992a) there has been very little analytical work on htn planners. ....

....conflicts caused by the interactions among tasks. For example, in Figure 4, if we use up all our money in order to rent the car, we may not be able to see a show. The job of finding and resolving such interactions is performed by critics. Historically speaking, critics were introduced into noah (Sacerdoti, 1977) to identify and deal with several kinds of interactions (not just deleted preconditions) among the different networks used to reduce each non primitive operator. This is reflected in Steps 6 and 7 of Figure 3: after each reduction, a set of critics is checked so as to recognize and resolve ....

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Sacerdoti, E. D. A Structure for Plans and Behavior, Elsevier-North Holland. 1977.

....with our multiple cooperating agents approach to planning. In particular, this overall system may be unable to detect global problems with a plan, as each verifier only sees that the plan is locally correct . One such plan involves painting the ladder before painting the ceiling c.f. [Sac77]. This work does not deal with such interactions. 6 Conclusions In general, a planner must (correctly) know every fact relevant to any goal. This places quite a burden on both the planner itself, and to its author. One way around this problem is to distribute the information, forming sub modules ....

E.D. Sacerdoti. A Structure for Plans and Behaviour. Elsevier North-Holland, New York, 1977.

....is familiar from Prolog like languages, the multiplicative clauses provided by BI have a different interpretation which provides an account of local variables and interference in logic programming. An example will illustrate these ideas. Consider a simple version of the famous blocks world [41], in which a robotic arm is supposed to manipulate blocks, here labelled x , y and z. Suppose further that we wish to remove from the computation imagine perhaps that it is a construction process any components that may be defective. A sketch of a possible program P follows the diagram: x ....

E.D. Sacerdoti. A structure for Plans and Behaviour. Elsevier North Holland, 1977.

....is familiar from Prolog like languages, the multiplicative clauses provided by BI have a different interpretation which provides an account of local variables and interference in logic programming. An example will illustrate these ideas. Consider a simple version of the famous blocks world [23], in which a robotic arm is supposed to manipulate blocks, here labelled x , y and z. Suppose further that we wish to remove from the computation imagine perhaps that it is a construction process any components that may be defective. A sketch of a possible program P follows the diagram: ....

E.D. Sacerdoti. A structure for Plans and Behaviour. Elsevier North Holland, 1977.

....Scheduling Group, provides a generic domain independent computational architecture suitable for command, planning and execution applications. O Plan makes use of a variety of AI planning techniques, including a hierarchical planning system which can produce plans as partial orders on actions (cf. Sac77] an agenda based control architecture; incremental development of plan states ; temporal and resource constraint handling (cf. Ver83] and a number of data structures used in Nonlin [Tat77] which was the forerunner of O Plan. It therefore seemed that there would be considerable benefit in ....

E.D. Sacerdoti. A Structure for Plans and Behaviour. Artificial Intelligence. Elsevier North Holland, 1977.

....conflicts is one of the key issues for planning systems. The importance of this issue was realized as long ago as the 1970s in early AI planning systems such as strips [ Fikes and Nilsson, 1971 ] and hacker [ Sussman, 1990 ] The introduction of task networks and task decomposition in noah [ Sacerdoti, 1977 ] provided an even richer set of interactions and resolution methods, and a component of noah called the critic mechanism was designed for handling these interactions. Critics helped prune the search space by detecting dead ends in advance and by resolving many types of conflicts as soon as they ....

....ONR grant N00014 91 J1451. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or ONR. 1 Universal Method Composition Planner Some of the critics identified by Sacerdoti [ 1977 ] based in part on Sussman s [ 1990 ] earlier work) include: ffl Resolve Conflicts. The conflicts handled by this critic, later referred to as deleted condition interactions, have received the bulk of the attention in the literature. ffl Eliminate redundant preconditions. This critic both ....

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Sacerdoti, E. D. A Structure for Plans and Behavior, Elsevier-North Holland. 1977.

....3 To analyze the effect of external constraint on the correctness of the plan, as well as to modify the plan conservatively, the planner needs to represent and reason about the internal dependencies of its plans in a systematic fashion. Since, hierarchical nonlinear planning (e.g. noah [Sacerdoti, 1977] , nonlin [Tate, 1977] sipe [Wilkins, 1984] is the prominent method of abstraction and least commitment in domain independent planning, in this paper we will explore ways of extending it to handle the incrementality requirements of concurrent domains. In section 2, we will develop a precise ....

.... be seen as a process of reduction of abstract tasks into more concrete subtasks with the help of domain specific task reduction schemata, and resolving any harmful interactions by introduction of additional partial ordering relations among tasks or backtracking over previous decisions [Tate, 1977, Sacerdoti, 1977] Given a planning problem [I; G] where I is the specification of the initial state and G is the specification of the desired goal state (given as conjunction of literals to be satisfied) we use a structure called hierarchical task network (htn ) to represent the status of the plan at any ....

E.D. Sacerdoti. A Structure for Plans and Behavior. Elsevier North-Holland, New York, 1977.

....acts albeit control acts. Control acts, when performed, change the agent s intentions about carrying out acts. Our repertoire of control actions includes sequencing (for representing linear plans) conditional, iterative, disjunctive (equivalent to the OR splits of the Procedural Net formalism [25, 29]) conjunctive (ANDsplits) selective, and achieve acts (for goal based plan invocation) Sequencing Act: SEQUENCE(a 1 ; a 2 ) The acts a 1 and a 2 are performed in sequence. For example: SEQUENCE(PICKUP(A) PUT(A; TABLE) is the act of first picking up A and then putting it on the table. ....

Earl D. Sacerdoti. A Structure for Plans and Behavior. Elsevier North Holland, New York, NY, 1977.

....application along with the implementation of simulation based planning in the domain of Mission Planning. Possible future experiments related to Soar are also discussed. 1 [Key Words: Autonomy, Mission Planning, Computer Generated Forces, Multimodeling] 1 Introduction General purpose planners [12, 15, 14, 13] claim to solve planning problems for many different domains. 1 ISBN 0 8186 6440 1. Copyright(c) 1994 IEEE. All rights reserved. Personal use of this material is permitted. However, permission to reprint republish this material for advertising or promotional purposes or for creating new ....

E.D. Sacerdoti. A Structure for Plans and Behaviour. Elsevier-North Holland, 1977.

.... Key Process Knowledge Figure 1: TEXPAN system overview 6 The plan operator Each communicative act, including an illocutionary act and locutionary act, or a rhetorical relation is formalized as a plan operator (e.g. Figure 2 shows an example of plan operator) As in traditional planning paradigms (Sacerdoti 77) each plan operator defines the preconditions that must hold before a communicative act can be executed, the constraints on the occurring act, its intended effects, as well as its refinement or decomposition into sub actions. We follow Maybury s plan operator definition (Maybury 92) Both ....

Earl D. Sacerdoti. A structure for plans and behavior. Elsevier North-Holland, Inc., 1977.

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Sacerdoti E. D., A structure for plans and behavior, Elsevier-North Holland, 1977.

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Earl D. Sacerdoti. A Structure for Plans and Behavior. Elsevier North-Holland, 1977.

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E.D. Sacerdoti. A Structure for Plans and Behavior. Elsevier North-Holland, New York, 1977.

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E.D. Sacerdoti. A Structure for Plans and Behavior. Elsevier /North Holland, 1977.

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Sacerdoti E. D., A structure for plans and behavior, Elsevier-North Holland, 1977.

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