Inverse coefficient problem for a fully fractional diffusion equation with nonlinear and source nonlocal initial condition

Abstract

In this work, we consider an inverse problem of determining a time dependent coefficient in a fully fractional diffusion equation with a nonlinear source term. The nonlocal initial-boundary value problem refers to the forward model: the fractional diffusion equation equipped with a nonlocal initial condition and homogeneous Dirichlet boundary conditions. We first establish the existence and uniqueness of the mild solution to this nonlocal initial boundary value problem, together with the corresponding regularity properties of the solution. These results are obtained via the Fourier method, tools from fractional calculus, and key properties of the Mittag-Leffler function. Subsequently, by applying a fixed-point argument in suitable Sobolev spaces, we prove a theorem on the local existence and uniqueness of the solution to the inverse problem. In this way, we establish the well-posedness of the problem solution.