(=> (= (Matrix-Of-Columns @Elements) ?M)
(= (Column ?I ?M) (Nth (Listof @Elements) ?I)))
(=> (= (Column ?M ?I) ?L)
(Forall (?J) (= (Value ?M ?J ?I) (Value ?L ?J 1))))
(=> (= (Column ?M ?I) ?L) (= (Row-Dimension ?M) (Row-Dimension ?L)))
(=> (= (Column ?M ?I) ?L) (Column-Matrix ?L))
(=> (= (Column ?M ?I) ?L) (=< ?I (Column-Dimension ?M)))
(=> (= (Column ?M ?I) ?L) (Positive-Integer ?I))
(=> (= (Column ?M ?I) ?L) (Matrix ?M))
(=> (= (Matrix-Less-Row-And-Column ?A ?I ?J) ?B)
(Defined (Column ?A ?J)))
(=> (= (Matrix-Less-Column ?A ?I) ?B) (Defined (Column ?A ?I)))