1,721,006 research outputs found

    N=p-harmonic maps: Regularity for the sphere case

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    We introduce n/pα-harmonic maps as critical points of the energy En;pα (v)= Rn δ α /2 v pα where pointwise v W D n → SN-1, for the N-sphere SN-1 RN and pα D n/α . This energy combines the non-local behaviour of the fractional harmonic maps introduced by Rivière and the first author with the degenerate arguments of the n-Laplacian. In this setting, we will prove Hölder continuity. © 2014 de Gruyter

    Partial Regularity for Stationary Solutions to Liouville-Type Equation in dimension 3

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    In dimension n=3n=3, we prove that the singular set of any stationary solution to the Liouville equation Δu=eu-\Delta u=e^u, which belongs to W1,2W^{1,2}, has Hausdorff dimension at most 11

    On the Bellman equation for infinite horizon problems with unbounded cost functional

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    We study a class of infinite horizon control problems for nonlinear systems, which includes the Linear Quadratic (LQ) problem, using the Dynamic Programming approach. Sufficient conditions for the regularity of the value function are given. The value function is compared with sub- and supersolutions of the Bellman equation and a uniqueness theorem is proved for this equation among locally Lipschitz functions bounded below. As an application it is showed that an optimal control for the LQ problem is nearly optimal for a large class of small unbounded nonlinear and non-quadratic pertubations of the same problem

    Symmetry properties of viscosity solutions to nonlinear uniformly elliptic equations

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    \begin{abstract}We study uniformly elliptic fully nonlinear equations F(D2u,Du,u,x)=0, F(D^2u, Du, u, x)=0, and prove results of Gidas-Ni-Nirenberg type for positive viscosity solutions of such equations. We show that symmetries of the equation and the domain are reflected by the solution, both in bounded and unbounded domains

    On the Bellman equation for some unbounded control problems.

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    We consider a class of finite horizon optimal control problems with unbounded data for nonlinear systems, which includes the Linear-Quadratic (LQ) problem. We give comparison results between the value function and viscosity sub- and supersolutions of the Bellman equation, and prove uniqueness for this equation among locally Lipschitz functions bounded below. As an application we show that an optimal control for the LQ problem is nearly optimal for a large class of small unbounded nonlinear and non-quadratic perturbations of the same problem

    On the Generalized Dirichlet Problem for Viscous Hamilton-Jacobi Equations,

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    AbstractWe study the Dirichlet problem for viscous Hamilton–Jacobi equations. Despite this type of equations seems to be uniformly elliptic, loss of boundary conditions may occur because of the strong nonlinearity of the first-order part and therefore the Dirichlet boundary condition has to be understood in the sense of viscosity solutions theory. Under natural assumptions on the initial and boundary data, we prove a Strong Comparison Result which allows us to obtain the existence and the uniqueness of a continuous solution which is defined globally in time

    Finite Time Horizon Risk Sensitive Control and the RobustLimit under a Quadratic Growth Assumption

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    The finite time--horizon risk sensitive limit problem for continuous, nonlinear systems is considered. Previous results are extended to cover more typical examples. In particular, the cost may grow quadratically, and the diffusion coefficient may depend on the state. It is shown that the risk sensitive value function is the solution of the corresponding dynamic programming equation. It is also shown that this value converges to the value of the Robust control problem as the cost becomes infinitely risk averse with corresponding scaling of the diffusion coefficient

    Free boundary minimal surfaces: a nonlocal approach

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    Given a smooth closed embedded manifold N and a compact connected smooth Riemannian surface (S, g) with boundary, we consider half-harmonic maps from the boundary of S to N. These maps are critical points of the nonlocal energy given by the Dirichlet energy of the harmonic extension of u in S. We express this energy as a sum of the half-energies at each boundary component, plus a quadratic term which is continuous in the smooth topology. We show the regularity of half-harmonic maps. We also establish a connection between free boundary minimal surfaces and critical points of E with respect to variations of the pair (map, metric), in terms of the Teichmüller space of S
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