Editing KL-ONE (section)

==Overview==
There is a whole family of KL-ONE-like systems. One of the innovations that KL-ONE initiated was the use of a [[deductive classifier]], an automated reasoning engine that can validate a frame ontology and deduce new information about the ontology based on the initial information provided by a domain expert. 

Frames in KL-ONE are called [[concepts]]. These form hierarchies using subsume-relations; in the KL-ONE terminology a [[superclass (computer science)|super class]] is said to subsume its [[Subclass (computer science) | subclasses]]. 
[[Multiple inheritance]] is allowed. Actually a concept is said to be well-formed only if it inherits from more than one other concept. All concepts, except the top concept (usually THING), must have at least one super class. 

In KL-ONE descriptions are separated into two basic classes of concepts: primitive and defined. Primitives are domain concepts that are not fully defined. This means that given all the properties of a concept, this is not sufficient to classify it. They may also be viewed as incomplete definitions. Using the same view, defined concepts are complete definitions. Given the properties of a concept, these are [[necessary and sufficient]] conditions to classify the concept.

The slot-concept is called roles and the values of the roles are role-fillers. There are several different types of roles to be used in different situations. The most common and important role type is the generic RoleSet that captures the fact that the role may be filled with more than one filler.