English

The Morse property for functions of Kirchhoff-Routh path type

Analysis of PDEs 2020-12-03 v1

Abstract

For a bounded domain ΩRn\Omega\subset\mathbb{R}^n let HΩ:Ω×ΩRH_\Omega:\Omega\times\Omega\to\mathbb{R} be the regular part of the Dirichlet Green function for the Laplace operator. Given a fixed arbitrary C2{\mathcal C}^2 function f:DRf:{\mathcal D}\to\mathbb{R}, defined on an open subset DRnN{\mathcal D}\subset\mathbb{R}^{nN}, and fixed coefficients λ1,,λNR{0}\lambda_1,\dots,\lambda_N\in\mathbb{R}\setminus\{0\} we consider the function fΩ:DΩNRf_\Omega:{\mathcal D}\cap\Omega^N\to\mathbb{R} defined as fΩ(x1,,xN)=f(x1,,xN)j,k=1NλjλkHΩ(xj,xk). f_\Omega(x_1,\dots,x_N) = f(x_1,\dots,x_N) - \sum_{j,k=1}^N \lambda_j\lambda_k H_\Omega(x_j,x_k). We prove that fΩf_\Omega is a Morse function for most domains Ω\Omega of class Cm+2,α{\mathcal C}^{m+2,\alpha}, any m0m\ge0, 0<α<10<\alpha<1. This applies in particular to the Robin function h:ΩRh:\Omega\to\mathbb{R}, h(x)=HΩ(x,x)h(x)=H_\Omega(x,x), and to the Kirchhoff-Routh path function where ΩR2\Omega\subset\mathbb{R}^2, {\mathcal D}=\{x\in\mathbb{R}^{2N}: \text{x_j\ne x_kfor for j\ne k}\}, and f(x1,,xN)=12πj,k=1jkNλjλklogxjxk. f(x_1,\dots,x_N) = - \frac{1}{2\pi}\sum_{\genfrac{}{}{0pt}{}{j,k=1}{j\ne k}}^N\lambda_j\lambda_k\log|x_j-x_k|.

Keywords

Cite

@article{arxiv.1708.09315,
  title  = {The Morse property for functions of Kirchhoff-Routh path type},
  author = {Thomas Bartsch and Anna Maria Micheletti and Angela Pistoia},
  journal= {arXiv preprint arXiv:1708.09315},
  year   = {2020}
}

Comments

14 pages