Modular density of smooth functions in inhomogeneous and fully anisotropic Musielak–Orlicz–Sobolev spaces

Abstract

We provide a universal and precise description of a family of inhomogeneous and fully anisotropic weak N-functions M:Ω×Rn→[0,∞) that generate function spaces of Musielak–Orlicz–Sobolev type in which smooth functions are dense in a natural topology.