Exact solutions for fractional partial differential equations by a new fractional sub-equation method

In this paper, we propose a new fractional sub-equation method for finding exact solutions of fractional partial differential equations (FPDEs) in the sense of modified Riemann-Liouville derivative, which is the fractional version of the known (G /G) method. To illustrate the validity of this method, we apply it to the space-time fractional Fokas equation, the space-time fractional (2 + 1)-dimensional dispersive long wave equations and the space-time fractional fifth-order Sawada-Kotera equation. As a result, some new exact solutions for them are successfully established.