This work is supported by the NNSF of China(No.10371065);the NSF of Shandong Province,China(No.Z2002A01)
In this paper, we prove several results concerning meromorphic functions f and g of hyperorder less than one such that f^(j) and g^(j) have the same zeros and poles for j=0, 1, 2. We provide some examples to show ...