Inverse-Initial Problem for Time-Degenerate PDE Involving the Bi-Ordinal Hilfer Derivative

The authors have proved a unique solvability of an inverse-initial problem for a time-fractional degenerate partial differential equation. Using a method of separation of variables, they obtained the Cauchy problem for fractional differential equation involving the bi-ordinal Hilfer derivative in time-variable. The authors present the solution to this Cauchy problem in an explicit form via the Kilbas–Saigo function. Further, using the upper and lower bounds of the function, they prove uniform convergence of infinite series corresponding to the solution of the formulated inverse-initial problem.