Functional Analysis-H=W Musielak spaces framework, by Youssef Ahmida, Alberto Fiorenza and Ahmed Youssfi, communicated on 13 December 2019.

Wc give a sufficient structural condition on the Musielak functions for the Meyers-Scrrin theorem to hold in Musielak spaces. Wc unify and extend some density results of smooth functions in Orlicz Sobolcv spaces as well as in variable exponent Sobolev spaces.