Class of the matrices with only one column
(<=> (Column-Matrix ?M)
(And (Matrix ?M) (= (Column-Dimension ?M) 1)))
(Matrix ?M)
(<= (Column-Dimension $X 1) (Column-Matrix $X))
(<=> (Column-Matrix ?M)
(And (Matrix ?M) (= (Column-Dimension ?M) 1)))
(Nth-Domain Column 3 Column-Matrix)
(=> (= (Column ?M ?I) ?L) (Column-Matrix ?L))