摘要
In this paper, we give necessary and sufficient conditions for oscillation of bounded solutions of nonlinear second order difference equation △(pn△yn)+ qnf(yn-rn) = 0. Obtained results improve theorems in the literature [3,6,7].
在本文中,我们给出了非线性二阶差分方程△（pn△yn）+qnf（yn-rn）=0有界解振动的充分必要条件和比较定理,所得结果推广了文[3,6,7]的相应定理。
基金
Supported by the National Natural Science Foundation of China (19571023)
the Natural Science Foundation of Hebei province (100139)
