6.1. Path-Based Inference as Generalized Inheritance

Another way for Cassie to infer information is via path-based inference. This is a generalization of the notion of inheritance found in other semantic-network formalisms.

Begin by setting up a knowledge base about various animals:

(resetnet t)
(define object isa has)
(describe (assert object elephant isa animal))
(describe (assert object circus\ elephant isa elephant))
(describe (assert object Dumbo isa circus\ elephant))
(describe (assert object Clyde isa elephant))
(describe (assert object bird isa animal))
(describe (assert object Tweety isa bird))
(describe (assert object animal has head))
(describe (assert object head has mouth))
(describe (assert object elephant has trunk))
(describe (assert object trunk isa appendage))