for A, B, C, D being Real
for h, g being Function of (TOP-REAL 2),(TOP-REAL 2) st A > 0 & C > 0 & h = AffineMap (A,B,C,D) & g = AffineMap ((1 / A),(- (B / A)),(1 / C),(- (D / C))) holds
( g = h " & h = g " )