Banach spaces containing $c_0$ and elements in the fourth dual

Antonio Avilés, Gonzalo Martínez-Cervantes, Abraham Rueda Zoca

A recent result of T.~Abrahamsen, P.~Hájek and S.~Troyanski states that a separable Banach space is almost square if and only if there exists $h\in S_{X^{\ast \ast \ast \ast }}$ such that $\|x+h\|…