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Liouville theorems for mixed local and nonlocal indefinite equations

Pengyan Wang, Leyun Wu

Abstract

We investigate the qualitative properties of positive solutions to mixed local-nonlocal equations with indefinite nonlinearities, emphasizing the interaction between classical and fractional Laplacians. We first establish maximum principles and prove strict monotonicity along the $x_1$-direction for mixed elliptic operators. By combining a mollified first eigenfunction with a suitable sub-solution, we derive nonexistence results for the mixed operator $ (-Δ)^s - Δ$ via a contradiction argument. These results are further extended to the parabolic setting, incorporating both the Marchaud-type fractional time derivative and the classical first-order derivative, revealing new qualitative features under dual nonlocality. A key aspect of our approach is a careful adaptation of the method of moving planes to the mixed local-nonlocal context. By addressing the distinct scaling behaviors of local and nonlocal terms, the method yields monotonicity and Liouville-type results without standard decay assumptions, and provides a framework potentially applicable to a broader class of mixed elliptic and parabolic problems.

Liouville theorems for mixed local and nonlocal indefinite equations

Abstract

We investigate the qualitative properties of positive solutions to mixed local-nonlocal equations with indefinite nonlinearities, emphasizing the interaction between classical and fractional Laplacians. We first establish maximum principles and prove strict monotonicity along the -direction for mixed elliptic operators. By combining a mollified first eigenfunction with a suitable sub-solution, we derive nonexistence results for the mixed operator via a contradiction argument. These results are further extended to the parabolic setting, incorporating both the Marchaud-type fractional time derivative and the classical first-order derivative, revealing new qualitative features under dual nonlocality. A key aspect of our approach is a careful adaptation of the method of moving planes to the mixed local-nonlocal context. By addressing the distinct scaling behaviors of local and nonlocal terms, the method yields monotonicity and Liouville-type results without standard decay assumptions, and provides a framework potentially applicable to a broader class of mixed elliptic and parabolic problems.
Paper Structure (4 sections, 9 theorems, 243 equations)

This paper contains 4 sections, 9 theorems, 243 equations.

Key Result

Theorem 1.1

Let $u(x )\in C^2(\mathbb R^n)\cap {\mathcal{L}}_{2s}$ is a positive bounded classical solution of equation v1. Suppose that $u$ is uniformly continuous and the following conditions hold: (F1):$f$ is strictly increasing in $x_1$ and (F2):$g$ is locally Lipschitz and nondecreasing in $(0,+\infty)$. Moreover, $g'(u)$ is continuous near $u=0$, Then $u(x )$ is strictly monotone increasing in the $

Theorems & Definitions (24)

  • Theorem 1.1
  • Remark 1.2
  • Theorem 1.3
  • Remark 1.4
  • Theorem 1.5
  • Theorem 1.6
  • Remark 1.7
  • Lemma 2.1
  • Remark 2.2
  • proof : Proof of Lemma \ref{['lemf4']}
  • ...and 14 more