The Banach space JT is primary
The James' tree space JT is an example due to R. C. James of a Banach space with nonseparable dual which does not contain \(\ell_ 1\). Here it is proved that for every bounded linear operator U on JT there is a subspace \(X\subset JT\), isometric to JT, such that either U or (I-U) acts isomorphically on X and either UX or (I-U)X is complemented in JT. As a consequence, JT is primary.
scientific article; zbMATH DE number 3849854