There are control systems with delay [1]
There are differential equations with fractional order:
$$D^\alpha x(t)=f(t,x(t))$$
I am wondering why we see control systems with delay and fractional order ODE together a lot in many researches such as [2], [3], [4], [5]?
Is there any relationship between control system with time delay and fractional order to bind them together? or we see them together just because both are under control theory?
I also have found this quote from here:
Therefore, the fractional models are a good and natural alternative to the known classical non-local equations called “delay differential equations”