摆动并且第四份订单的 asymptotic 行为非线性的差别方程

）,where f（n,y）may be classified as superlinear,sublinear,strongly super-linear and strongly sublinear.In superlinear and sublinear cases,necessary and sufficient conditionsare obtained for the difference equation to admit the existence of nonoscillatory solutions with specialasymptotic properties.In strongly superlinear and strongly sublinear cases,sufficient conditions aregiven for all solutions to be oscillatory.