let V be RealUnitarySpace; :: thesis: for W1, W2 being Subspace of V holds the carrier of (W1 /\ W2) c= the carrier of (W1 + W2)
let W1, W2 be Subspace of V; :: thesis: the carrier of (W1 /\ W2) c= the carrier of (W1 + W2)
( the carrier of (W1 /\ W2) c= the carrier of W1 & the carrier of W1 c= the carrier of (W1 + W2) ) by Lm2, Lm4;
hence the carrier of (W1 /\ W2) c= the carrier of (W1 + W2) ; :: thesis: verum