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6.5. Finding Information that Cassie Implicitly Believes

Now, this isn't all the animals. What we did was asked Cassie whom she explicitly believed to be an animal. What we probably would rather know is whom she can infer to be an animal. To do this, we can tell her that certain paths of relations are equivalent to certain relations. For instance, we can tell her that the isa relation is transitive. This is done with the define-path command, which takes a relation as its first argument and a path as its second. To define the path, we can use the compose command, which can be thought of as creating a new relation consisting of a path of relations. The path of relations might consist of zero or more (i.e., kstar) occurrences of certain relations, and we might want to restrict the path to go through only asserted nodes. (See UM§2.5.2 for a full description of the syntax and semantics of paths.) E.g., to tell Cassie that isa is transitive,

William J. Rapaport 2003-09-22