中文摘要：

讨论了带有Riemann-Liouville微分算子的分数阶微分方程初值问题,利用混合单调算子理论,获得了初值问题解的存在唯一性定理,并举例说明主要结果.

英文摘要：

In this paper, we discuss the initial value problem of fractional differential equations involving Riemann-Liouville differential operators. By means of the mixed monotone operator theory, we obtain the existence and uniqueness of the solutions to the initial value problem, and an example is given to illustrate the main result.