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PhysicalQuantity
subject			fact

PhysicalQuantity	documentation A PhysicalQuantity is a measure of some quantifiable aspect of the modeled world, such as 'the earth's diameter' (a constant length) and 'the stress in a loaded deformable solid' (a measure of stress, which is a function of three spatial coordinates). All PhysicalQuantities are either ConstantQuantities or FunctionQuantities. Instances of ConstantQuantity are dependent on a UnitOfMeasure, while instances of FunctionQuantity are Functions that map instances of ConstantQuantity to other instances of ConstantQuantity (e.g., TimeDependentQuantities are FunctionQuantities). Although the name and definition of PhysicalQuantity is borrowed from physics, PhysicalQuantities need not be material. Aside from the dimensions of length, time, velocity, etc., nonphysical dimensions such as currency are also possible. Accordingly, amounts of money would be instances of PhysicalQuantity. PhysicalQuantities are distinguished from Numbers by the fact that the former are associated with a dimension of measurement
	is partitioned into ConstantQuantity, FunctionQuantity
	is a kind of Quantity
Quantity	is first domain of AdditionFn
	is first domain of DivisionFn
	is first domain of ExponentiationFn
	is first domain of greaterThan
	is first domain of greaterThanOrEqualTo
	is first domain of lessThan
	is first domain of lessThanOrEqualTo
	is first domain of MaxFn
	is first domain of MinFn
	is first domain of MultiplicationFn
	is first domain of ReciprocalFn
	is first domain of RemainderFn
	is first domain of RoundFn
	is first domain of SubtractionFn
	is second domain of AdditionFn
	is second domain of DivisionFn
	is second domain of greaterThan
	is second domain of greaterThanOrEqualTo
	is second domain of lessThan
	is second domain of lessThanOrEqualTo
	is second domain of MaxFn
	is second domain of MinFn
	is second domain of MultiplicationFn
	is second domain of RemainderFn
	is second domain of SubtractionFn
Abstract	has axiom (<=> (instance ?ABS Abstract) (not (exists (?POINT) (or (located ?ABS ?POINT) (existant ?ABS ?POINT)))))
	is disjoint from Physical

Kinds of PhysicalQuantity :

• ConstantQuantity (63 kinds, 333 facts) - A ConstantQuantity is a PhysicalQuantity which has a constant value, e.g. 3 meters and 5 hours. The magnitude (see MagnitudeFn) of every ConstantQuantity is a RealNumber. ConstantQuantities are distinguished from FunctionQuantities, which map ConstantQuantities to other ConstantQuantities. All ConstantQuantites are expressed with the BinaryFunction MeasureFn, which takes a Number and a UnitOfMeasure as arguments. For example, 3 Meters can be expressed as (MeasureFn 3 Meter). ConstantQuantities 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)
• FunctionQuantity (60 kinds, 180 facts) - A FunctionQuantity is a Function that maps from one or more instances of ConstantQuantity to another instance of ConstantQuantity. For example, the velocity of a particle would be represented by a FunctionQuantity mapping values of time (which are ConstantQuantities) to values of distance (also ConstantQuantities). Note that all instances of FunctionQuantity are Functions with a fixed arity. Note too that all elements of the range of a FunctionQuantity have the same physical dimension as the FunctionQuantity itself
• UnitOfMeasure (76 kinds, 332 facts) - A standard of measurement for some dimension. For example, the Meter is a UnitOfMeasure for the dimension of length, as is the Inch. There is no intrisic property of a UnitOfMeasure that makes it primitive or fundamental; rather, a system-of-units (e.g. SystemeInternationalUnit) defines a set of orthogonal dimensions and assigns units for each

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