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An elliptic semilinear equation with source term involving boundary measures: the subcritical case.

Marie Françoise Bidaut-Véron, Laurent Vivier (2000)

Revista Matemática Iberoamericana

We study the boundary behaviour of the nonnegative solutions of the semilinear elliptic equation in a bounded regular domain Ω of RN (N ≥ 2),⎧   Δu + uq = 0,   in Ω⎨⎩   u = μ,      on ∂Ωwhere 1 < q < (N + 1)/(N - 1) and μ is a Radon measure on ∂Ω. We give a priori estimates and existence results. The lie on the study of superharmonic functions in some weighted Marcinkiewicz spaces.

Approximation of harmonic functions

Björn E. J. Dahlberg (1980)

Annales de l'institut Fourier

Let u be harmonic in a bounded domain D with smooth boundary. We prove that if the boundary values of u belong to L p ( σ ) , where p 2 and σ denotes the surface measure of D , then it is possible to approximate u uniformly by function of bounded variation. An example is given that shows that this result does not extend to p < 2 .

Brownian motion and generalized analytic and inner functions

Alain Bernard, Eddy A. Campbell, A. M. Davie (1979)

Annales de l'institut Fourier

Let f be a mapping from an open set in R p into R q , with p > q . To say that f preserves Brownian motion, up to a random change of clock, means that f is harmonic and that its tangent linear mapping in proportional to a co-isometry. In the case p = 2 , q = 2 , such conditions signify that f corresponds to an analytic function of one complex variable. We study, essentially that case p = 3 , q = 2 , in which we prove in particular that such a mapping cannot be “inner” if it is not trivial. A similar result for p = 4 , q = 2 would solve...

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