let V be RealLinearSpace; :: thesis: for W1, W2 being Subspace of V holds W1 /\ W2 = W2 /\ W1
let W1, W2 be Subspace of V; :: thesis: W1 /\ W2 = W2 /\ W1
the carrier of (W1 /\ W2) = the carrier of W2 /\ the carrier of W1 by Def2;
hence W1 /\ W2 = W2 /\ W1 by Def2; :: thesis: verum