A partial answer to Brezis' Open Problem 2.1
Abstract
In this paper, we give a partial answer to Brezis' Open Problem~2.1, which concerns the uniqueness of solutions to the Ginzburg--Landau equation in the unit disc with the degree-one boundary condition. Let λ1 be the first Dirichlet eigenvalue of −Δ in the unit disc and set ε*:=λ1−1/2. We prove that there exists δ>0 such that the radial solution is the unique weak solution for every ε∈(ε*−δ,∞). More generally, we establish the analogous uniqueness result for the Ginzburg--Landau system on bounded connected C1,1 domains in ℝN, 2≤ N≤4, with nontrivial boundary data. In particular, uniqueness persists slightly below the convexity threshold ε*, where the strict convexity argument is no longer available. The proof combines strict convexity for ε≥ε* with a compactness argument, nondegeneracy of the solution at ε=ε* and the implicit function theorem.
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BibTeX
@misc{ji2026partial,
title = {{A partial answer to Brezis' Open Problem 2.1}},
author = {Chao Ji and Kai Sheng},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.21896},
eprint = {2608.21896},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.21896},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A partial answer to Brezis' Open Problem 2.1
AU - Chao Ji
AU - Kai Sheng
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2608.21896
UR - https://arxiv.org/abs/2608.21896
AB - In this paper, we give a partial answer to Brezis' Open Problem~2.1, which concerns the uniqueness of solutions to the Ginzburg--Landau equation in the unit disc with the degree-one boundary condition. Let λ_1 be the first Dirichlet eigenvalue of −Δ in the unit disc and set ε_*:=λ_1^−1/2. We prove that there exists δ>0 such that the radial solution is the unique weak solution for every ε∈(ε_*−δ,∞). More generally, we establish the analogous uniqueness result for the Ginzburg--Landau system on bounded connected C^1,1 domains in ℝ^N, 2≤ N≤4, with nontrivial boundary data. In particular, uniqueness persists slightly below the convexity threshold ε_*, where the strict convexity argument is no longer available. The proof combines strict convexity for ε≥ε_* with a compactness argument, nondegeneracy of the solution at ε=ε_* and the implicit function theorem.
ER -