EN
Let E be a separable Banach space with the λ-bounded approximation property. We show that for each ϵ > 0 there is a Banach space F with a Schauder basis such that E is isometrically isomorphic to a 1-complemented subspace of F and, moreover, the sequence (Tₙ) of canonical projections in F has the properties
$sup_{n∈ ℕ } ||Tₙ|| ≤ λ + ϵ$ and $limsup_{n→ ∞} ||Tₙ|| ≤ λ$.
This is a sharp quantitative version of a classical result obtained independently by Pełczyński and by Johnson, Rosenthal and Zippin.