On functions having coincident ρ-norms

Abstract

In a measure space (X;A; μ) we consider two measurable functions ƒ; g : E → R for some E ∈ A. We characterize the property of having equal p-norms when ρ varies in an infinite set P in [1;+∞). In a first theorem we consider the case of bounded functions when P is unbounded with ∑p∈P(1/p) = +∞ . The second theorem deals with the possibility of unbounded functions, when P has a finite accumulation point in [1, + ∞ ).