Plan reuse versus plan generation : a theoretical and empirical analysis

The ability of a planner to reuse parts of old plans is hypothesized to be a valuable tool for improving efficiency of planning by avoiding the repetition of the same planning effort. We test this hypothesis from an analytical and empirical point of view. A comparative worst-case complexity analysis of generation and reuse under different assumptions reveals that it is not possible to achieve a provable efficiency gain of reuse over generation. Further, assuming "conservative" plan modification, plan reuse can actually be strictly more difficult than plan generation. While these results do not imply that there won\u27t be an efficiency gain in the "average case", retrieval of a good plan may present a serious bottleneck for plan reuse systems, as we will show. Finally, we present the results of an empirical study of three different plan reuse systems, which leads us to the conclusion that the utility of plan-reuse techniques is limited and that these limits have not been determined yet

Plan modifications versus plan generation : a complexity-theoretic perspective

The ability of a planner to modify a plan is considered as a valuable tool for improving efficiency of planning by avoiding the repetition of the same planning effort. From a computational complexity point of view, however, it is by no means obvious that modifying a plan is computationally as easy as planning from scratch if the modification has to follow the principle of "conservatism", i.e., to reuse as much of the old plan as possible. Indeed, considering propositional STRIPS planning, it turns out that conservative plan modification is as hard as planning and can sometimes be harder than plan generation. Furthermore, this holds even if we consider modification problems where the old and the new goal specification are similar. We put these results into perspective and discuss the relationship to existing plan modification systems. Although sometimes claimed otherwise, these systems do not address the modification problem, but use a non-conservative form of plan modification as a heuristic technique

Deductive planning and plan reuse in a command language environment

In this paper we introduce a deductive planning system currently being developed as the kernel of an intelligent help system. It consists of a deductive planner and a plan reuse component and with that provides planning from first as well as planning from second principles. Both components rely upon an interval-based temporal logic. The deductive formalisms realizing plan formation from formal specifications and the reuse of already existing plans respectively are presented and demonstrated by examples taken from an operating system\u27s domain

Planning from second principles : a logic-based approach

In this paper, a logical formalization of planning from second principles is proposed, which relies on a systematic decomposition of the planning process. Deductive inference processes with clearly defined semantics formalize planning from second principles. Plan modification is based on a deductive approach which yields provably correct modified plans. Reusable plans are retrieved from a dynamically created plan library using terminological logic as a query language to the library. Apart from sequential plans, this approach enables a planner to efficiently reuse and modify plans containing control structures like conditionals and iterations

University of Minnesota Morris Teacher Education Retention Survey

Field Project Presented in Fulfillment of the Requirements for the Master of Education Degree in the College of Education and Human Service Professions By Jana Koehler, University of Minnesota Duluth, April 2016. 1 computer file (PDF); 76 pages, appendices A-D, tables. This item has been modified from the original to redact the signatures present.The purpose of this study was to determine if the University of Minnesota, Morris (UMM) teacher education graduates retention rates fall in line with the research that has previously been conducted.University of Minnesota, Duluth. College of Education and Human Service Professions

PHI : a logic-based tool for intelligent help systems

We introduce a system which improves the performance of intelligent help systems by supplying them with plan generation and plan recognition components. Both components work in close mutual cooperation. We demonstrate two modes of cross-talk between them, one where plan recognition is done on the basis of abstract plans provided by the planner and the other where optimal plans are generated based on recognition results. The examples which are presented are taken from an operating system domain, namely from the UNIX mail domain. Our system is completely logic-based. Relying on a common logical framework--the interval-based modal temporal logic LLP which we have developed--both components are implemented as special purpose inference procedures. Plan generation from first and second principles is provided and carried out deductively, whereas plan recognition follows a new abductive approach for modal logics. The plan recognizer is additionally supplied with a probabilistic reasoner as a means to adjust the help provided for user-specific characteristics

07061 Abstracts Collection -- Autonomous and Adaptive Web Services

From 4.2.2007 to 9.2.2007, the Dagstuhl Seminar 07061 ``Autonomous and Adaptive Web Services\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Integrated plan generation and recognition : a logic-based approach

The work we present in this paper is settled within the field of intelligent help systems. Intelligent help systems aim at supporting users of application systems by the achievements of qualified experts. In order to provide such qualified support our approach is based on the integration of plan generation and plan recognition components. Plan recognition in this context serves to identify the users goals and so forms the basis for an active user support. The planning component dynamically generates plans which are proposed for the user to reach her goal. We introduce a logic-based approach where plan generation and plan recognition is done on a common logical basis and both components work in some kind of cross-talk

An overview of assessment methodology for obesity-related variables in infants at risk

Background: The first 2 years of a child’s life are a particularly critical time period for obesity prevention. Aim: An increasing amount of research across the world is aimed at understanding factors that impact early childhood obesity and developing interventions that target these factors effectively. With this growing interest, new and interdisciplinary research teams are developing to meet this research need. Due to rapid growth velocity during this phase of the lifespan, typical assessments used in older populations may not be valid or applicable in infants, and investigators need to be aware of the pros and cons of specific methodological strategies. Methods: This paper provides an overview of methodology available to assess obesity-related factors in the areas of anthropometry and body composition, nutrient intake, and energy expenditure in infants aged 0–2 years. Results: Gold standard measures for body composition, such as dual-energy X-ray absorptiometry (DXA) or other imaging techniques, are costly, require highly trained personnel, and are limited for research application. Nutrient intake methodology primarily includes surveys and questionnaires completed via parent proxy report. In terms of energy expenditure, methods of calorimetry are expensive and may not differentiate between different activities. Questionnaires or physical activity sensors offer another way of energy expenditure assessment. However, questionnaires have a certain recall bias, while the sensors require further validation. Conclusions: Overall, in addition to understanding the pros and cons of each assessment tool, researchers should take into consideration the experience of the interdisciplinary team of investigators, as well as the cost and availability of measures at their institution

X-ray dark-field signal reduction due to hardening of the visibility spectrum

X-ray dark-field imaging enables a spatially-resolved visualization of small-angle X-ray scattering. Using phantom measurements, we demonstrate that a material's effective dark-field signal may be reduced by modification of the visibility spectrum by other dark-field-active objects in the beam. This is the dark-field equivalent of conventional beam-hardening, and is distinct from related, known effects, where the dark-field signal is modified by attenuation or phase shifts. We present a theoretical model for this group of effects and verify it by comparison to the measurements. These findings have significant implications for the interpretation of dark-field signal strength in polychromatic measurements.Comment: 11 pages, 6 figures. Previously submitted to IEEE Transactions on Medical Imagin