Order and hyper-order of solutions of second order linear differential equations (Q2021680)

In this paper, the authors investigate the growth of solutions of second order linear differentilal equations. They determine new conditions on the coefficients in order that every non-trivial solution has an infinite order by introducing the notions of function extremal to Yang's inequality and extremal to Denjoy's conjecture. They also study the hyper-order of these solutions. Moreover, they extend these results to higher order linear differential equations. So this work is interesting.