theorem :: RMOD_3:42

for R being Ring
for V being strict RightMod of R
for W1, W2 being Submodule of V holds
( W1 + W2 = V iff for v being Vector of V ex v1, v2 being Vector of V st
( v1 in W1 & v2 in W2 & v = v1 + v2 ) ) by Lm14;