Geometry of the Marcinkiewicz Sequence Space

Abstract

We characterise the real extreme points of the unit ball of m 0 Ψ , the complex extreme points of the unit ball of m Ψ and the real extreme and exposed points of the unit ball of (m 0 Ψ ) . Using these characterisations we show that, depending on the length of the extreme points, the multipliers of m 0 Ψ are either constant multiple of the identity or diagonal operators.