"The definition of fractional derivative is very important. You know, consideringt the case of advanced calculus, we should define the measure firstly, and then we can define the fractional derivative. While the measure is related to fractal sets, it is not so easy to define a new reasonable and applicable one since fractal objects in our real world, On the other hand, are not really fractals. "
I mean, we should define or use a fractional derivatie from measure of the sets logically, which is more reasonable. And it's useful in real applications.