Technical Reports (CIS)

Document Type

Technical Report

Date of this Version

May 1991


University of Pennsylvania Department of Computer and Information Science Technical Report No. MS-CIS-91-33.


This paper describes an efficient connectionist knowledge representation and reasoning system that combines rule-based reasoning with reasoning about inheritance and classification within an IS-A hierarchy. In addition to a type hierarchy, the proposed system can encode generic facts such as 'Cats prey on birds' and rules such as 'if x preys on y then y is scared of x' and use them to infer that Tweety (who is a Canary) is scared of Sylvestor (who is a Cat). The system can also encode qualified rules such as 'if an animate agent walks into a solid object then the agent gets hurt'. The proposed system can answer queries in time that is only proportional to the length of the shortest derivation of the query and is independent of the size of the knowledge base. The system maintains and propagates variable bindings using temporally synchronous - i.e., in-phase - firing of appropriate nodes.



Date Posted: 28 January 2008