Publications

Papers on EXPECT

Papers on Planning

Abstract: Ontologies are becoming a recognized vehicle for knowledge reuse, knowledge sharing, and modeling. This paper presents PLANET, an ontology for representing plans. To show that PLANET is a comprehensive ontology that can be reused to build new applications, we describe several specializations of it to represent plans in three different real-world domains that were made by adding minor extensions to PLANET's general definitions and classes. In past work, we have developed several plan evaluation systems in these domains, and have integrated them in several occasions with plan editors and plan generation systems. For each of these integrations, and often for each system in the integration, a new format for exchanging plans was devised. PLANET can represent all of the plans that we and others have used in these domains, providing a standard universal format for knowledge sharing that can be used as an interlingua in integrated planning applications. Finally, the paper discusses how we have used PLANET as a knowledge modelling tool to design representations for courses of action in a military domain, guiding us to make useful distinctions and modelling choices.

Abstract: In order to support a wide range of planning-related activities, we argue that plan and action representations must move to a more expressive language for goals and capabilities than is found in most current systems. A structured representation for capabilities can make explicit a hierarchy of capabilities based on subsumption, resulting in benefits for reasoning, representing, and acquiring operators and plans. By making capabilities more easily understandable to humans, such a representation can also benefit mixed-initiative approaches. We present a structured representation of capabilities and a subsumption-based matcher for it. We then describe three existing systems that use this approach in different kinds of planning tasks and tools. We finish with a discussion of how plan generation systems can benefit from using this representation.

Andre Valente, Jim Blythe, Yolanda Gil, and William Swartout. "On the Role of Humans in Enterprise Control Systems: the Experience of INSPECT". In The DARPA-JFACC Symposium on Advances in Enterprise Control, San Diego, November 1999 (PDF file )

Abstract: In this paper, we use the example of a successful mixed-initiative plan evaluation tool for the domain of air campaign planning to argue that the human-in-the-loop is an important feature of enterprise control systems. Our tool, called INSPECT, evaluates air campaign plans and alerts the user about inconsistencies and potential problems. A generalization of INSPECT called PSMTool is also capable of limited interaction with a subject matter expert to capture new critiques of plans. The paper describes our work on INSPECT and PSMTool, analyzes the key contributions of these tools, and draws some conclusions about the role of mixed-initiative tools in enterprise control systems.

Andre Valente, Yolanda Gil, and William Swartout. "INSPECT: A Tool to Evaluate Air Campaign Plans". Internal Project Report. (PDF file )

Abstract: INSPECT is a mixed-initiative plan evaluation tool in the domain of air campaign planning that has been a central component of several major DARPA demonstrations of integrated planning environments and tools. The creation process of an air campaign plan is manually driven at its higher levels, and because plans are complex and always changing they often (our experience says always) contain errors or inconsistencies. INSPECT evaluates user-generated plans and alerts the user about inconsistencies and potential problems. INSPECT has received wide acceptance by air campaign planning experts, and is currently undergoing new extensions and further integrations with other tools in this domain. The paper describes our work on INSPECT, analyzes the key contributions of this tool, and draws some conclusions about the design and integration of planning applications.

Abstract: EXPECT provides an environment for developing knowledge-based systems that allows end-users to add new knowledge without needing to understand the details of system organization and implementation. The key to EXPECT's approach is that it understands the structure of the knowledge-based system being built: how it solves problems and what knowledge it needs to support problem-solving. EXPECT uses this information to guide users in maintaining the knowledge-based system. We have used EXPECT to develop a tool for evaluating transportation plans.

Abstract: It is hard to evaluate in current planning applications what aspects of the approach address each of the complexities of the problem. This results from the fact that the planning community is lacking a vocabulary to describe planning tasks and applications. This work is an effort towards descriptions of planning applications in terms that are useful 1) to extract conclusions from particular implementations, 2) to facilitate cross-comparisons among different planners applied to the same problem, and 3) to facilitate comparisons among different tasks. We analyze the Sisyphus experience, a 3-year old and still ongoing effort in the knowledge acquisition community to enable a cross-comparison of their application systems as they implement a common pre-stated problem description. Based on this experience, we propose a set of dimensions to describe applications that distinghish between descriptions of the properties of the architecture, the type of problem, and the data sets. We show how they can be used to produce useful distictions in the context of the first Sisyphus task, which was an office assignment problem. Our hope is that the same dimensions will be useful to other researchers in describing and characterizing their applications, as well as a useful point of comparison for future Sisyphus efforts.

Abstract: This document is the result of a joint effort to understand what are relevant factors to consider when there are several possible courses of action (COAs) to accomplish a Non-combatant Evacuation Operation (NEO) military mission. These relevant factors are useful for generation and evaluation of COAs and provide the basis for a good decision in selecting a COA. The document compiles the relevant factors from the perspective of logistics that are useful to evaluate whether or not alternative proposed COAs can be supported logistically, and which ones seem to be better alternatives compared to the others. The ultimate goal of this joint effort is to use these factors to automate the evaluation and comparison of COAs and use the comparison to determine what are critical aspects of a COA that may be changed to produce a better option with a generative planner. We discuss how we envision using EXPECT and O-Plan2 for this purpose.

Related Papers

Jim Blythe, "Decision-Theoretic Planning", AI Magazine, Summer 1999 ( PDF file)

Abstract: The recent advances in computer speed and algorithms for probabilistic inference have led to a resurgence of work on planning under uncertainty. The aim is to design AI planners for environments where there may be incomplete or faulty information, where actions may not always have the same results and where there may be tradeoffs between the different possible outcomes of a plan. Addressing uncertainty in AI planning algorithms will greatly increase the range of potential applications but there is plenty of work to be done before we see practical decision-theoretic planning systems. This article outlines some of the challenges that need to be overcome and surveys some of the recent work in the area.

Andre Valente, Yolanda Gil, and Jim Blythe. "A Representation and Library for Force Support Objectives in Air Campaign Plans". USC/ISI Technical Report, 1998.

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