Regularity results for fully nonlinear parabolic integro-differential operators

In this paper, we consider the regularity theory for fully nonlinear parabolic integro-differential equations with symmetric kernels. We are able to find parabolic versions of Alexandrov–Backelman–Pucci estimate with $0<\sigma <2$ . And we show a Harnack inequality, Hölder regularity, and $C^{1,\alpha }$ -regularity of the solutions by obtaining decay estimates of their level sets.     

Regularity for anisotropic fully nonlinear integro-differential equations

We consider fully nonlinear integro-differential equations governed by kernels that have different homogeneities in different directions. We prove a nonlocal version of the ABP estimate, a Harnack inequality and the interior \(C^{1, \gamma }\) regularity, extending the results of Caffarelli and Silvestre (Comm Pure Appl Math 62:597–638, 2009) to the anisotropic case.     

Regularity and uniqueness of the first eigenfunction for singular fully nonlinear operators

For singular elliptic fully-nonlinear operators we prove that the eigenfunctions corresponding to the principal eigenvalues in bounded domains are simple. The proof uses in particular a regularity result obtained in the first part of the paper which is of independent interest.     

An inverse spectral problem for integro-differential Dirac operators with general convolution kernels

ABSTRACT

An integro-differential Dirac system with a convolution kernel consisting of four independent functions is considered. We prove that the kernel is uniquely determined by specifying the spectra of two boundary value problems with one common boundary condition. The proof is based on the reduction of this nonlinear inverse problem to solving some nonlinear integral equation, which we solve globally. On this basis we also obtain a constructive procedure for solving the inverse problem along with necessary and sufficient conditions for its solvability in an appropriate class of kernels.     

Regularity results for stable-like operators

For α[1,2) we consider operators of the form

and for α(0,1) we consider the same operator but where the f term is omitted. We prove, under appropriate conditions on A(x,h), that any solution u to will be in C^α+β if fC^β.     

Harnack inequality for singular fully nonlinear operators and some existence results

In this article we further advance in the theory of singular fully nonlinear operators modeled on the q-laplacian proving a Harnack inequality. We provide also several applications of this inequality and the ideas used for proving it. In doing so we have left various open questions, all of them related to the fact that the operator is not sub-linear.     

Eigenvalue estimates of positive integral operators with analytic kernels

In this paper, we exhibit canonical positive definite integral kernels associated with simply connected domains. We give lower bounds for the eigenvalues of the sums of such kernels.     

Symmetry results for nonlinear elliptic operators with unbounded drift

We prove the one-dimensional symmetry of solutions to elliptic equations of the form ?div(e ^G(x) a(|?u|)?u) = f(u) e ^G(x), under suitable energy conditions. Our results holds without any restriction on the dimension of the ambient space.     

Regularity results for quasilinear elliptic systems with nonlinear boundary conditions

It is proved that a solution of the boundary-value problem for a second-order quasilinear system with controlled order of nonlinearity is partially smooth all the way to the boundary of a domain. The boundary condition is imposed by means of a second-order nonlinear operator which can be regarded as a generalization of the “directional derivative” to the case of quasilinear systems. Bibliography: 6 titles. Translated fromProblemy Matematicheskogo Analiza, No. 14, 1995, pp. 23–50.