Author Description

Excerpt from Planning With Resources <p>Situation-dependent Operators, or operators whose effects are dependent on the situation in which they are performed, are disallowed in most previous planners as the associated reasoning mechanisms become computationally intractable (chapman, sipe (wilkins, 1988) is the notable exception, and provides a variety of heuristics for managing the complexity resulting from an expressive representation. However, if we restrict our focus to situation-dependent operators that consume and produce resources, which are ubiquitous in many real-world domains construction planning, process planning), efficient and provably correct planners can be developed. <p>It is often natural to express goals the desired quantity of some product) in terms of resources. The strips representation may be extended as follows toallow the specification of effects to consume or produce quantities of resources.1 Step preconditions now specify, in addition to a set of propositions, the amounts of resources that must be available in order for a step to be performed. Effects now specify the amounts of resources that are consumed or produced by a step. Similarly, the initial state, I, must now specify the initial resource allocations, and the goal state, G, must specify the desired final amounts of resources. <p>Most classical planners did not emphasize resource considerations, primarily because resource management was viewed as part of the scheduling problem, which was viewed as distinct from the planning problem. For example, isis (fox, ajob-shop scheduling system assumes that resources are allocated and tasks scheduled only after the task network has been planned. However, there are good reasons for including resource considerations during planning: 1) it is often natural to express some planning goals the desired quantity of some product) in terms of resources; 2) resource constraints may determine whether a given planning problem is solvable; 3) resource consid