I read about fractional partial differential equation on wiki and I now know its an expansion of the usual integral power partial differential equation. I also read that it had some applications in fluid and light. etc. modeling.
However, I still have some confusions, could you explain the following questions?
First, I read that for any $a>0, (P^af)=f'$ exists. However, is it unique?
Further, could you give an exact form(in calculation) that what's a half-derivative? https://en.wikipedia.org/wiki/Fractional_calculus
Could you give some examples of the mathematical models/application(better with link to articles) of which the fractional partial differential equation were applied?
What's the limitation to the fractional partial differential equation and its recent development?
Can we replace or approximate fractional partial differential equation with usual integral partial differential equation?