English

A direct proof of the equivalence between Dirichlet's principle and Perron's method

Analysis of PDEs 2025-11-25 v1

Abstract

We give a short proof that for a bounded domain ΩRn\Omega\subset\mathbb{R}^n and continuous boundary data gC(Ω)g\in C(\partial\Omega) admitting a continuous finite-energy extension ϕH1(Ω)C(Ωˉ)\phi\in H^{1}(\Omega)\cap C(\bar\Omega), the minimizer of the Dirichlet energy E(v)=Ωv2dx,vϕH01(Ω), E(v) = \int_{\Omega} |\nabla v|^{2}\,dx, \qquad v-\phi\in H^{1}_{0}(\Omega), coincides with the Perron solution hgh_g of the Dirichlet problem Δu=0\Delta u = 0 in Ω\Omega with boundary data gg. The argument stays entirely in H1(Ω)H^{1}(\Omega) and uses only strong convergence via strict convexity of the Dirichlet energy, Friedrichs' inequality, Weyl's lemma, and Wiener's exhaustion by regular subdomains. No weak convergence, Poisson problems with distributional right hand sides, or general elliptic theory are needed.

Keywords

Cite

@article{arxiv.2511.18762,
  title  = {A direct proof of the equivalence between Dirichlet's principle and Perron's method},
  author = {Tsogtgerel Gantumur},
  journal= {arXiv preprint arXiv:2511.18762},
  year   = {2025}
}

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5 pages