Complemented and uncomplemented subspaces of Banach spaces (Q2708480)

This is a survey paper on some aspects of complemented subspaces. Here, the authors focus primarily on nonseparable spaces and treat topics like decomposability of (nonseparable) Banach spaces, the separable complementation property, projectional resolutions of the identity, topological properties of the dual unit ball, bounded projectional resolutions. In particular, the authors give a simple proof of the Amir-Lindenstrauss theorem on projectional resolutions of the identity in WCG spaces that appears here for the first time in roman alphabet.