“…In [11], Marcinkiewicz defined the class ^€ P (R), 1 ^ p < oo 9 as the set of Borel measurable By identifying functions whose difference has zero norm, he proved that {^£ rp {R), || ||) is actually a Banach space. The space had been studied by many authors in the theory of almost periodic functions and generalized harmonic analysis (e.g., Besicovitch [4], Bohr and Folner [6], Bertrandias [3] and Lau and Lee [10]). In [10], it was shown that the transformation defined in (1.1) In particular, every function in W" P {R), 1 < p < oo, is an extreme point of S(^t p (R)).…”