【摘要】 <正> 在[4]里我们证明了如果实数α、β、γ不同时满足β≤γ=α-4,γ>0, 微分算式aD²x^αD²+bx^β+icx^γ在I=[1,∞]上是极限点的,其中a,b,c是正数,而当β=γ=α-4,γ>0时,存在正数σ使得微分算式D²x^γ+4D²+σ（1+i）x^γ不是极限点。本文将讨论剩下的更多还原

【Abstract】 This paper is a sequel of the previous work [4]. Here, we deal with the case: β<γ=α-4 and γ>0 which has not been considered in that paper. Now, using Kauffman’s method, the following theorem has been obtained: Let M≡αD²x^γ+4D²+icxγ, γ>0, and L≡M+bx^β, where β<γ, a,b, c are positive numbers. If T₁（M） is separated, then L is limit-point and T₁（L） is separated.更多还原