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ConstantQuantity |
A ConstantQuantity is a PhysicalQuantity that has a constant value, e.g. 3 Meters and 5 HourDurations. The magnitude (see MagnitudeFn) of every ConstantQuantity is a RealNumber. ConstantQuantity is distinguished from FunctionQuantity, in that each instance of the latter is formed through the mapping of one PhysicalQuantity to another PhysicalQuantity. Each instance of ConstantQuantity is expressed with the BinaryFunction MeasureFn, which takes a Number and a UnitOfMeasure as arguments. For example, 3 Meters is expressed as (MeasureFn 3 Meter). Instances of ConstantQuantity form a partial order (see PartialOrderingRelation) with the lessThan relation, since lessThan is a RelationExtendedToQuantities and lessThan is defined over the RealNumbers. The lessThan relation is not a total order (see TotalOrderingRelation) over the class ConstantQuantity since elements of some subclasses of ConstantQuantity (such as length quantities) are incomparable to elements of other subclasses of ConstantQuantity (such as mass quantities).
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| Instances | Abstract | 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. |
| | BinaryPredicate | A Predicate relating two items - its valence is two. |
| | BinaryRelation | BinaryRelations are relations that are true only of pairs of things. BinaryRelations are represented as slots in frame systems. |
| | Entity | The universal class of individuals. This is the root node of the ontology. |
| | InheritableRelation | The class of Relations whose properties can be inherited downward in the class hierarchy via the subrelation Predicate. |
| | Predicate | A Predicate is a sentence-forming Relation. Each tuple in the Relation is a finite, ordered sequence of objects. The fact that a particular tuple is an element of a Predicate is denoted by '(*predicate* arg_1 arg_2 .. arg_n)', where the arg_i are the objects so related. In the case of BinaryPredicates, the fact can be read as `arg_1 is *predicate* arg_2' or `a *predicate* of arg_1 is arg_2'. |
| | Relation | The Class of relations. There are two kinds of Relation: Predicate and Function. Predicates and Functions both denote sets of ordered n-tuples. The difference between these two Classes is that Predicates cover formula-forming operators, while Functions cover term-forming operators. |
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