Class of the matrices that can be inverted
(<=> (Invertible-Matrix ?M)
(And (Square-Matrix ?M) (Not (Zero-Element (Determinant ?M)))))
(Not (Zero-Element (Determinant ?M))) (Square-Matrix ?M)
(<=> (Invertible-Matrix ?M)
(And (Square-Matrix ?M)
(Exists (?M-1)
(And (Square-Matrix ?M-1)
(Identity-Matrix (* ?M ?M-1))
(Identity-Matrix (* ?M-1 ?M))))))
(<=> (Invertible-Matrix ?M)
(And (Square-Matrix ?M) (Not (Zero-Element (Determinant ?M)))))
(=> (Matrix-Inverse $X $Y) (Invertible-Matrix $Y))
(=> (Matrix-Inverse $X $Y) (Invertible-Matrix $X))
(=> (= (Matrix-Inverse ?M) ?M-1) (Invertible-Matrix ?M-1))
(=> (= (Matrix-Inverse ?M) ?M-1) (Invertible-Matrix ?M))