Some approximation properties in fractional Musielak-Sobolev spaces

In this article, we show some density properties of smooth and compactly supported functions in fractional Musielak-Sobolev spaces essentially extending the results of Fiscella, Servadei, and Valdinoci obtained in the fractional Sobolev setting. The proofs of these properties are mainly based on a basic technique of convolution, joined with a cutoff, with some care needed in order not to exceed the original support.