Dirichlet Problem For P-harmonic Functions Research Articles

The Perron method for varvec{p}-harmonic functions in unbounded sets in mathbf {R}^n and metric spaces

The Perron method for solving the Dirichlet problem for p-harmonic functions is extended to unbounded open sets in the setting of a complete metric space with a doubling measure supporting a p-Poincaré inequality, 1<p<infty . The upper and lower (p-harmonic) Perron solutions are studied for open sets, which are assumed to be p-parabolic if unbounded. It is shown that continuous functions and quasicontinuous Dirichlet functions are resolutive (i.e., that their upper and lower Perron solutions coincide), that the Perron solution agrees with the p-harmonic extension, and that Perron solutions are invariant under perturbation of the function on a set of capacity zero.

The Dirichlet problem for p-harmonic functions with respect to the Mazurkiewicz boundary, and new capacities

In this paper we develop the Perron method for solving the Dirichlet problem for the analog of the p-Laplacian, i.e. for p-harmonic functions, with Mazurkiewicz boundary values. The setting considered here is that of metric spaces, where the boundary of the domain in question is replaced with the Mazurkiewicz boundary. Resolutivity for Sobolev and continuous functions, as well as invariance results for perturbations on small sets, are obtained. We use these results to improve the known resolutivity and invariance results for functions on the standard (metric) boundary. We also illustrate the results of this paper by discussing several examples.

The obstacle and Dirichlet problems associated with p-harmonic functions in unbounded sets in R^n and metric spaces

We study the obstacle problem for unbounded sets in a proper metric measure space supporting a (p,p)-Poincare inequality. We prove that there exists a unique solution. We also prove that if the measure is doubling and the obstacle is continuous, then the solution is continuous, and moreover p-harmonic in the set where it does not touch the obstacle. This includes, as a special case, the solution of the Dirichlet problem for p-harmonic functions with Sobolev type boundary data.

The Dirichlet Problem for p-Harmonic Functions on a Network

The Dirichlet Problem for p-Harmonic Functions on a Network

Dirichlet problem at infinity on Gromov hyperbolic metric measure spaces

We study the asymptotic Dirichlet problem for p-harmonic functions in a very general setting of Gromov hyperbolic metric measure spaces.

The Perron method for p-harmonic functions in metric spaces

We use the Perron method to construct and study solutions of the Dirichlet problem for p-harmonic functions in proper metric measure spaces endowed with a doubling Borel measure supporting a weak (1, q)-Poincaré inequality (for some 1⩽ q< p). The upper and lower Perron solutions are constructed for functions defined on the boundary of a bounded domain and it is shown that these solutions are p-harmonic in the domain. It is also shown that Newtonian (Sobolev) functions and continuous functions are resolutive, i.e. that their upper and lower Perron solutions coincide, and that their Perron solutions are invariant under perturbations of the function on a set of capacity zero. We further study the problem of resolutivity and invariance under perturbations for semicontinuous functions. We also characterize removable sets for bounded p-(super)harmonic functions.

The Dirichlet problem for p-harmonic functions on metric spaces

We study the Dirichlet problem for p-harmonic functions (and p-energy minimizers) in bounded domains in proper, pathconnected metric measure spaces equipped with a doubling measure and supporting a Poincare inequality. The Dirichlet problem has previously been solved for Sobolev type boundary data, and we extend this result and solve the problem for all continuous boundary data. We study the regularity of boundary points and prove the Kellogg property, i.e. that the set of irregular boundary points has zero p-capacity. We also construct p-capacitary, p-singular and p-harmonic measures on the boundary. We show that they are all absolutely continuous with respect to the p-capacity. For p = 2 we show that all the boundary measures are comparable and that the singular and harmonic measures coincide. We give an integral representation for the solution to the Dirichlet problem when p = 2, enabling us to extend the solvability of the problem to L-1 boundary data in this case. Moreover, we give a trace result for Newtonian functions when p = 2. Finally, we give an estimate for the Hausdorff dimension of the boundary of a bounded domain in Ahlfors Q-regular spaces. (Less)

The Dirichlet problem at infinity for random walks on graphs with a strong isoperimetric inequality

We study the spatial behaviour of random walks on infinite graphs which are not necessarily invariant under some transitive group action and whose transition probabilities may have infinite range. We assume that the underlying graphG satisfies a strong isoperimetric inequality and that the transition operatorP is strongly reversible, uniformly irreducible and satisfies a uniform first moment condition. We prove that under these hypotheses the random walk converges almost surely to a random end ofG and that the Dirichlet problem forP-harmonic functions is solvable with respect to the end compactification If in addition the graph as a metric space is hyperbolic in the sense of Gromov, then the same conclusions also hold for the hyperbolic compactification in the place of the end compactification. The main tool is the exponential decay of the transition probabilities implied by the strong isoperimetric inequality. Finally, it is shown how the same technique can be applied to Brownian motion to obtain analogous results for Riemannian manifolds satisfying Cheeger's isoperimetric inequality. In particular, in this general context new (and simpler) proofs of well known results on the Dirichlet problem for negatively curved manifolds are obtained.