let R be Ring; for V being LeftMod of R
for W being with_Linear_Compl Submodule of V
for L being Linear_Compl of W holds W + L = ModuleStr(# the carrier of V, the addF of V, the ZeroF of V, the lmult of V #)
let V be LeftMod of R; for W being with_Linear_Compl Submodule of V
for L being Linear_Compl of W holds W + L = ModuleStr(# the carrier of V, the addF of V, the ZeroF of V, the lmult of V #)
let W be with_Linear_Compl Submodule of V; for L being Linear_Compl of W holds W + L = ModuleStr(# the carrier of V, the addF of V, the ZeroF of V, the lmult of V #)
let L be Linear_Compl of W; W + L = ModuleStr(# the carrier of V, the addF of V, the ZeroF of V, the lmult of V #)
V is_the_direct_sum_of W,L
by Th124;
hence
W + L = ModuleStr(# the carrier of V, the addF of V, the ZeroF of V, the lmult of V #)
; verum