let V be Z_Module; :: thesis: for W1, W2 being Submodule of V holds (0). W1 = (0). W2
let W1, W2 be Submodule of V; :: thesis: (0). W1 = (0). W2
(0). W1 = (0). V by Th51;
hence (0). W1 = (0). W2 by Th51; :: thesis: verum