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Abstract
subject			fact

Abstract	documentation Properties or qualities as distinguished from any particular embodiment of the properties/qualities in a physical medium. Instances of Abstract can be said to exist in the same sense as mathematical objects such as sets and relations, but they cannot exist at a particular place and time without some physical encoding or embodiment
	has axiom (<=> (instance ?ABS Abstract) (not (exists (?POINT) (or (located ?ABS ?POINT) (existant ?ABS ?POINT)))))
	is disjoint from Physical
	is a kind of Entity
Entity	is first domain of documentation
	is first domain of element
	is first domain of equal
	is first domain of IdentityFn
	is first domain of instance
	is first domain of relatedExternalConcept
	is first domain of relatedInternalConcept
	is second domain of destination
	is second domain of equal
	is second domain of identityElement
	is second domain of inScopeOfInterest
	is second domain of patient
	is second domain of refers
	is second domain of relatedInternalConcept
	is second domain of represents
	is second domain of representsForAgent
	is second domain of representsInLanguage

Kinds of Abstract :

• Attribute (63 kinds, 199 facts) - Qualities which we cannot or choose not to reify into subclasses of Object
• Class (326 kinds, 2276 facts) - Class generalizes Set. Classes, like Sets, are collections of things. Accordingly, the notion of membership is generalized as well - a member of a Class is an instance the Class. Classes can differ from Sets in two important respects. First, Classes that are not explicitly identified as Sets are not assumed to be extensional. That is, distinct Classes might well have exactly the same instances. Second, Classes typically have an associated `condition' that determines the instances of the Class. So, for example, the condition `human' determines the Class of Humans. Note that some Classes might satisfy their own condition (e.g., the Class of Abstract things is Abstract) and hence be instances of themselves
• Proposition (15 kinds, 40 facts) - Propositions are Abstract entities that express a complete thought or a set of such thoughts. As an example, the formula '(instance Yojo Cat)' expresses the Proposition that the entity named Yojo is an element of the Class of Cats. Note that propositions are not restricted to the content expressed by individual sentences of a Language. They may encompass the content expressed by theories, books, and even whole libraries. It is important to distinguish Propositions from the ContentBearingObjects that express them. A Proposition is a piece of information, e.g. that the cat is on the mat, but a ContentBearingObject is an Object that represents this information. A Proposition is an abstraction that may have multiple representations: strings, sounds, icons, etc. For example, the Proposition that the cat is on the mat is represented here as a string of graphical characters displayed on a monitor and/or printed on paper, but it can be represented by a sequence of sounds or by some non-latin alphabet or by some cryptographic form
• Quantity (148 kinds, 659 facts) - Any specification of how many or how much of something there is. Accordingly, there are two subclasses of Quantity: Number (how many) and PhysicalQuantity (how much)

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