=C2=A0 Actually we have the following situation: $3D"H_1\=$ are
=C2=A0Hilbert spaces, a map = $3D"\Phi:H_1\to$ and we set $3D"=$ . Then by the energy estima= tes we have:
=C2=A0 1. $3D"\{x_n\}"$ is bounded in $3D"H_1"$ ;=C2=A0 2. $3D"\=$ is Cauchy in $3D"H_2"$ (by the contraction).=