Criteria for monotonicity properties of Musielak-Orlicz spaces equipped with the Amemiya norm

Criteria for strict monotonicity, lower local uniform monotonicity, upper local uniform monotonicity, and uniform monotonicity of Musielak-Orlicz spaces over any a-finite and complete measure space, endowed with the Amemiya norm are given. The fact that the spaces are considered over arbitrary a-finite measure space is essential because, as it is shown in Example 3, the Musielak-Orlicz spaces need not be strictly monotone even if their restrictions to the nonatomic part and the purely atomic part are strictly monotone. (C) 2004 Elsevier Inc. All rights reserved.