Building and Refining Abstract Planning Cases by Change of Representation Language

ion is one of the most promising approaches to improve the performance of problem solvers. In several domains abstraction by dropping sentences of a domain description -- as used in most hierarchical planners -- has proven useful. In this paper we present examples which illustrate significant drawbacks of abstraction by dropping sentences. To overcome these drawbacks, we propose a more general view of abstraction involving the change of representation language. We have developed a new abstraction methodology and a related sound and complete learning algorithm that allows the complete change of representation language of planning cases from concrete to abstract. However, to achieve a powerful change of the representation language, the abstract language itself as well as rules which describe admissible ways of abstracting states must be provided in the domain model. This new abstraction approach is the core of Paris (Plan Abstraction and Refinement in an Integrated System), a system in which abstract planning cases are automatically learned from given concrete cases. An empirical study in the domain of process planning in mechanical engineering shows significant advantages of the proposed reasoning from abstract cases over classical hierarchical planning.Comment: See http://www.jair.org/ for an online appendix and other files accompanying this articl

A hierarchical systems formulation of the rural development process in developing countries

A very urgent and significant set of problems facing developing countries arises in the area of rural development. The reasons for this are that the majority of the populations of these countries lives in the rural areas and the fact that the level of production in the rural areas has a major effect on the overall economy of the developing countries. In this paper hierarchical systems theory is applied to rural development. The latter is complex in the sense that it is multidimensional, highly interacting and stochastic in nature, whilst reliable causal explanations of its socio-economic aspects in particular are commonly not availables Here a multilevel/hierarchical formulation of the rural development system is presented and analysed to provide an improved conceptual framework for the design, phasing and inter-connection of component management procedures which together comprise an effective rural development planning and control system. This analysis has been applied to design an initial set of procedures which have been introduced and tested in six rural areas of Kenya. These provide at the first level a short cycle of one month for plan implementation and at the second level a medium cycle of one year for plan reformulation. These and further procedural components are being considered for replication in all rural areas of Kenya as an integral part of the introduction of district level development plans in the context of the third five year plan (1974-79). Although the main benefits arising from the application of systems analysis to date have been at the level of procedural and institutional innovation,the multilevel/hierarchical formulation described in this paper now lays a foundation for a more quantitative approach based on systematic assembly of data describing the operation of the rural development system. ventually, simulation studies using sophisticated planning models will enable a more efficient selection between alternative rural development strategies, projects and programmes