“…The properties of the restricted Dirichlet fractional Laplacian (− ) a Dir defined in the introduction were studied e.g. in Blumenthal and Getoor [6], Landkof [34], Hoh and Jacob [29], Kulczycki [33], Chen and Song [14], Jakubowski [31], Silvestre [44], Caffarelli and Silvestre [11], Frank and Geisinger [21], Ros-Oton and Serra [36], [37], Felsinger, Kassmann and Voigt [20], Grubb [25], [26], Bonforte, Sire and Vazquez [8], Servadei and Valdinoci [43], Binlin, Molica Bisci and Servadei [5], and many more papers referred to in these works (see in particular the list in [43]).…”