- is the binary subtraction operator for physical-quantities. This is a polymorphic extension of the same function over real numbers as defined in the kif-numbers ontology.All quantity objects have an additive inverse and the addition of a parameter and its additive-inverse will equal a zero element, such as the real number 0 or the zero vector of the same dimension if ?x is a vector. Each engineering quantity algebra will define specialization of + for its domain wirth a zero element.
and also:
If $tau$ and $tau_1$, ..., $tau_n$ denote numbers, then the term {tt (- $tau$ $tau_1 ... tau_n$)} denotes the difference between the
number denoted by $tau$ and the numbers denoted by $tau_1$ through $tau_n$. An exception occurs when $n=0$, in which case the term denotes the negation of the number denoted by $tau$.
and also:
The - function is also defined for matrices, where it means the difference between two matrices (in the binary case) or additive inverse in the unary case.
and also:
The unary minus function is also defined for vector quantities.
(=> (And (Physical-Quantity ?X) (Physical-Quantity ?Y)) (<=> (- ?X ?Y ?Z) (= ?X (+ ?Y ?Z)))) (=> (Matrix ?A) (<=> (- ?A ?C) (And (Matrix ?C) (Forall (?I ?J) (=> (Defined (Value ?C ?I ?J)) (= (Value ?C ?I ?J) (- (Value ?A ?I ?J)))))))) (=> (And (Matrix ?A) (Matrix ?B) (= (Row-Dimension ?A) (Row-Dimension ?B)) (= (Column-Dimension ?A) (Column-Dimension ?B))) (<=> (- ?A ?B ?C) (And (Matrix ?C) (= (Row-Dimension ?A) (Row-Dimension ?C)) (= (Column-Dimension ?A) (Column-Dimension ?C)) (Forall (?I ?J) (=> (Defined (Value ?C ?I ?J)) (= (Value ?C ?I ?J) (- (Value ?A ?I ?J) (Value ?B ?I ?J)))))))) (=> (And (Vector-Quantity ?X) (- ?X ?Y)) (And (Vector-Quantity ?Y) (= (+ ?X ?Y) (The-Zero-Vector-Of-Type (Quantity.Dimension ?X) (Spatial.Dimension ?X)))))
(Undefined (Arity -)) (Undefined (Arity -)) (Undefined (Arity -)) (Undefined (Arity -)) (Undefined (Arity -)) (Undefined (Arity -)) (Undefined (Arity -)) (Undefined (Arity -))
(=> (And (Vector-Quantity ?X) (- ?X ?Y)) (And (Vector-Quantity ?Y) (= (+ ?X ?Y) (The-Zero-Vector-Of-Type (Quantity.Dimension ?X) (Spatial.Dimension ?X)))))