Approximation on variable exponent spaces by linear integral operators

This paper aims at approximation of functions by linear integral operators on variable exponent spaces associated with a general exponent function on a domain of a Euclidean space. Under a log-Holder continuity assumption of the exponent function, we present quantitative estimates for the approximation and solve an open problem raised in our earlier work. As applications of our key estimates, we provide high orders of approximation by quasi-interpolation type and linear combinations of Bernstein type integral operators on variable exponent spaces. We also introduce K-functionals and moduli of smoothness on variable exponent spaces and discuss their relationships and applications. (C) 2017 Elsevier Inc. All rights reserved.