“…Assumptions (A2) and (A5) are used commonly in the literature. For example, Liu [ 2 ], Yang [ 1 , 13 , 14 ], Yang [ 16 ], Liang [ 19 ], and Li [ 20 ] used (A5) , (A2) and (A4) were used by Liu [ 2 ] and Yang [ 1 , 13 , 14 ], (A3) and (A6) were assumed in Liu [ 2 ]. Assumption (A5) is easily satisfied, for example, choosing , , .…”