“…Suppose that for two fixed point iteration procedures {u n } ∞ n=0 and {v n } ∞ n=0 , both converging to the same fixed point p, the error estimates This concept turned out to be a very useful and versatile tool in studying the fixed point iterative schemes and hence various authors have used it, see [1]- [5], [18], [22], [23], [28], [32]- [34], [37]- [41], [40], [43]- [46], [55]- [57], [66], [68]- [72], [74], [78]- [81], to cite just an incomplete list. b…”