(=> (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))))))))