Averaging and orthogonal operators on variable exponent spaces L-p(.) (Omega)

Abstract

Given a measurable space (Omega, mu) and a sequence of disjoint measurable subsets A = (A(n))(n), the associated averaging projection P-A and the orthogonal projection T-A are considered. We study the boundedness of these operators on variable exponent spaces L-P(.) (Omega). These operators are unbounded in general. Sufficient conditions on the sequence A in order to achieve that P-A or T-A be bounded are given. Conditions which provide the boundedness of P-A imply that T-A is also bounded. The converse is not true. Some applications are given. In particular, we obtain a sufficient condition for the boundedness of the Hardy-Littlewood maximal operator on spaces L-P(.) (Omega).