“…A sound theory of fractional Orlicz-Sobolev spaces -a natural functional framework for these problems -is of course crucial in connection with their study. Properties of fractional Orlicz-Sobolev spaces are the subject of the contributions [2,3,4,5,10,16,31,39]. They provide extensions of some aspects of the theory of the classical fractional Sobolev spaces, which has been developed over the years -see e.g.…”