Special Session 60: Nonlinear Evolution Equations and Related Topics

Existence of time-fractional gradient flows for nonconvex energies in Hilbert spaces
Yoshihito Nakajima
Tohoku University
Japan
Co-Author(s):    Goro Akagi
Abstract:
This talk is concerned with the solvability of time-fractional gradient flow equations for nonconvex energies in Hilbert spaces. Main results consist of local and global (in time) existence of (continuous) strong solutions to time-fractional evolution equations governed by the difference of two subdifferential operators in Hilbert spaces. In contrast with classical evolution equations (with standard time-derivatives), there arise several new difficulties such as lack of chain-rule identity and low regularity of solutions from the subdiffusive nature of the problem. To prove the main results, integral forms of chain-rule formulae for time-fractional derivatives, a Lipschitz perturbation theory for time-fractional gradient flows for convex energies and Gronwall-type lemmas for nonlinear Volterra integral inequalities are developed. These abstract results are also applied to the Cauchy-Dirichlet problem for some $p$-Laplace subdiffusion equations with blow-up terms.