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The evolution equation and the eigenvalue problem for the Laplacian in a regular tree

Leandro M. Del Pezzo, Nicolas Frevenza, Julio D. Rossi

Abstract

In this paper, our main goal is to study the evolution problem associated with the Laplacian operator with Dirichlet boundary conditions on a regular tree. To this end, we place special emphasis on the associated first eigenvalue problem, which provides the fundamental tool for describing the long-time dynamics. First, we prove existence and uniqueness of solutions when the initial condition is compatible with the boundary condition. Next, we address the asymptotic behavior of the solutions and show that they decay to zero exponentially fast. This decay rate is determined by the associated first eigenvalue, which we also analyze in detail.

The evolution equation and the eigenvalue problem for the Laplacian in a regular tree

Abstract

In this paper, our main goal is to study the evolution problem associated with the Laplacian operator with Dirichlet boundary conditions on a regular tree. To this end, we place special emphasis on the associated first eigenvalue problem, which provides the fundamental tool for describing the long-time dynamics. First, we prove existence and uniqueness of solutions when the initial condition is compatible with the boundary condition. Next, we address the asymptotic behavior of the solutions and show that they decay to zero exponentially fast. This decay rate is determined by the associated first eigenvalue, which we also analyze in detail.

Paper Structure

This paper contains 7 sections, 29 theorems, 134 equations.

Key Result

Theorem 1.1

Let $\beta=0$. Then $\lambda$ is a principal eigenvalue of $\Delta_\beta$ if and only if $\lambda\in (0,1].$ Moreover, for every $\lambda \in (0,1],$ the function is an eigenfunction associated to $\lambda$.

Theorems & Definitions (50)

  • Theorem 1.1
  • Theorem 1.2
  • Proposition 1.3
  • Theorem 1.4
  • Theorem 1.5
  • Theorem 1.6
  • Theorem 1.7
  • Theorem 2.1: Maximum Principle
  • proof
  • Theorem 2.2: Comparison Principle
  • ...and 40 more