is a bounded linear functional on V . More precisely, the dual norm kλkV ¤ of λ
on V with respect to k·kV is less than or equal to the dual norm kbλk(V/W)¤ of bλ
on V/W with respect to the quotient norm k·kV/W, because of (6.3). Of course,
λ(v) = 0 for every v ∈ W, because q(v) = 0 when v ∈ W, by construction.
Conversely, suppose that λ is a bounded linear functional on V such that
λ(v) = 0 for every v ∈ W. As in Section 5, there is a linear functional bλ on
V/W that satisfies (7.1) for every v ∈ V . Note that