Reasoning with Incomplete Knowledge in a Resource-Limited Environment: Integrating Reasoning and Knowledge Acquisition

Abstract

This paper describes an approach to reasoning with incomplete information in a resource-limited environment. Approaches to date either assume infinite resources and proceed to enumerate a large inference space, or assume few resources and ignore the missing information. They do not reason about resource constraints and the inference methods admissible under them. A HEARSAY-11-like system is described where each knowledge source is a separate production system.' During rule evaluation, a rule antecedent is evaluated using minimal-resource methods. A rule antecedent is evaluated to true, false, or an expected resource cost to acquire the information necessary to complete its evaluation. If conflict resolution chooses a partially evaluatcd rule, it posts a goal asking other knowledge sources to provide the missing information, suspends the knowledge source, and informs the knowledge source's manager about the suspension and accompanying goal. The manager decides whether the goal is worth pursuing now, the amount of resources to apply to the task, what knowledge source to apply, and when to give up. The knowledge sources that attempt the goal can implement a variety of inferential and knowledge acquisition techniques.