On Brezis' First Open Problem: A Complete Solution
Liming Sun, Juncheng Wei, Wen Yang
TL;DR
The work resolves Brezis' Open Problem 1.1 in three dimensions by constructing infinitely many sign-changing solutions to the BN problem in the unit ball for any $\lambda>0$, employing a novel necklace of inverted crown bubbles rooted in Yamabe sign-changing solutions. Central to the approach are precise properties of the crown solution (non-degenerate, smooth nodal set) and a sophisticated inner–outer gluing scheme that translates an infinite-dimensional PDE problem into a finite-dimensional energy minimization over a carefully balanced parameter space. The authors develop an intricate energy expansion, manage long-range bubble interactions via contour-integral techniques for specific series, and perform a detailed multi-parameter analysis to locate an interior minimum, yielding a nontrivial, sign-changing solution with high Morse index. Their framework also provides a generalized Brezis–Open Problem result for strictly star-shaped 3D domains and offers a robust blueprint for tackling other critical-exponent elliptic problems using sign-changing building blocks and gluing methods.
Abstract
In 2023, H.\,Brezis published a list of his ``favorite open problems", which he described as challenges he had ``raised throughout his career and has resisted so far". We provide a complete resolution to the first one--Open Problem 1.1--in Brezis's favorite open problems list: the existence of solutions to the long-standing Brezis-Nirenberg problem on a three-dimensional ball. Furthermore, using the building blocks of Del Pino-Musso-Pacard-Pistoia sign-changing solutions to the Yamabe problem, we establish the existence of infinitely many sign-changing, nonradial solutions for the full range of the parameter.
