A Multi-Level Organization For Problem Solving Using Many, Diverse, Cooperating Sources Of Knowledge

Abstract

An organization is presented for implementing solutions to knowledge-based AI problems. The hypothesize-and-test paradigm is used as the basis for cooperation among many diverse and independent knowledge sources (KS's). The KS's are assumed individually to be errorful and incomplete. A uniform and integrated multi-level structure, the blQckboQrd, holds the current state of the system. Knowledge sources cooperate by creating, accessing, and modifying elements in the blackboard. The activation of a KS is datadriven, based on the occurrence of patterns in the blackboard which match templates specified by the knowledge source. Each level in the blackboard specifies a different representation of the problem space; the sequence of levels forms a loose hierarchy in which the elements at each level can approximately be described as abstractions of elements at the next lowe·r level. This decomposition can be thought of as an Q priori framework of a plan for solving the problem; each level is a generic stage in the plan.