Extremum Principle for Very Weak Solutions of <em>A</em>-harmonic Equation

Extremum Principle for Very Weak Solutions of <em>A</em>-harmonic Equation

Year:    2005

Journal of Partial Differential Equations, Vol. 18 (2005), Iss. 3 : pp. 235–240

Abstract

This paper deals with the very weak solutions of A-harmonic equation divA(x, ∇u(x)) = 0 (∗) where the operator A satisfies the monotonicity inequality, the controllable growth condition and the homogeneity condition. The extremum principle for very weak solutions of A-harmonic equation is derived by using the stability result of Iwaniec-Hodge decomposition: There exists an integrable exponent r_1 = r_1\left(p, n, \frac{β}{α}\right) = \frac{1}{2} \bigg[p - \frac{α}{100n²β} + \sqrt{\left(p + \frac{α}{100n²β}\right)² - \frac{4α}{100n²β}}\bigg] such that if u(x) ∈ W^{1, r}(Ω) is a very weak solution of the A-harmonic equation (∗), and m ≤ u(x) ≤ M on ∂Ω in the Sobolev sense, then m ≤ u(x) ≤ M almost everywhere in Ω, provided that r > r1. As a corollary, we prove that the 0-Dirichlet boundary value problem  {divA(x, ∇u(x)) = 0 u ∈ W^{1, r}_0 (Ω) of the A-harmonic equation has only zero solution if r > r_1.

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Journal Article Details

Publisher Name:    Global Science Press

Language:    English

DOI:    https://doi.org/2005-JPDE-5359

Journal of Partial Differential Equations, Vol. 18 (2005), Iss. 3 : pp. 235–240

Published online:    2005-01

AMS Subject Headings:   

Copyright:    COPYRIGHT: © Global Science Press

Pages:    6

Keywords:    A-harmonic equation