Self-Adjointness Of Products Of The Limit-Point Sturm-Liouville Operators
极限点型 Sturm-Liouville 算子乘积的自伴性

For the differential expression $l(y)=-(py')'+qy, \ t\in a,\infty)$, under the assumption that $l^k\ (k=1,2,3)$ are limit-pointed, the author studies the self-adjointness of the product operator $L_2L_1$, which $L_i\ (i=1,2)$ are generated by $l(y)$, and obtains a necessary and sufficient condition for self-adjointness of $L_2L_1$. Also, a necessary and sufficient condition for the self-adjointness of $L_3L_2L_1$, which $L_i\ (i=1,2,3)$ are associated with $l(y)=-y'+qy, \ t\in a,\infty)$, is obtained.