The so called Landis conjecture states that if a solution of the equation $$Δu+V(x)u=0$$ in an exterior domain decays faster than $e^{-κ|x|}$, for some $κ>\sqrt{\sup |V|}$, then it must be identically equal to $0$. This property can be viewed as a unique continuation at infinity (UCI) for solutions satisfying a suitable exponential decay. The Landis conjecture was disproved by Meshkov in the case of complex-valued functions, but it remained open in the real case. In the 2000s, several papers have addressed the issue of the UCI for linear elliptic operators with real coefficients. The results that have been obtained require some kind of sign condition, either on the solution or on the zero order coefficient of the equation. The Landis conjecture is still open nowadays in its general form. In the present paper, we start with considering a general (real) elliptic operator in dimension $1$. We derive the UCI property with a rate of decay $κ$ which is sharp when the coefficients of the operator are constant. In particular, we prove the Landis conjecture in dimension $1$, and we can actually reach the threshold value $κ=\sqrt{\sup |V|}$. Next, we derive the UCI property -- and then the Landis conjecture -- for radial operators in arbitrary dimension. Finally, with a different approach, we prove the same result for positive supersolutions of general elliptic equations.
Universidad del País Vasco / Euskal Herriko Unibertsitatea(巴斯克大学);BCAM – Basque Center for Applied Mathematics(巴斯克应用数学中心);Ikerbasque, Basque Foundation for Science(伊卡巴斯基克,巴斯克科学基金会);University of Cantabria(坎塔布里亚大学)
On Landis' conjecture in the plane for some equations with sign-changing potentials
本文研究了平面上椭圆型方程实值解的定量唯一连续性。在算子的一般假设下,建立了Landis猜想的定量形式.值得注意的是,我们证明了一个版本的Landis'猜想的解决方案,$-Δu + V u = 0$,其中$V$是一个有界函数的负部分表现出多项式衰减无穷大。证明背后的主要机制是结合迭代方案的消失估计的顺序。为了证明消失结果的阶,我们提出了一种新的构造正乘子的思想,并利用它将方程化为一个Beltrami系统。利用相似原理和阿达玛三准圆定理分析了一阶方程。
Sharp gradient bounds for uniformly elliptic PDE, eigenvalue asymptotics, and the Landis conjecture
PUC-Rio, Departamento de Matematica(天主教巴西里约热内卢大学数学系);Université Sorbonne Paris Nord, CNRS UMR 7539, Laboratoire Analyse, Géométrie et Applications(索邦巴黎北大学、法国国家科学研究中心7539联合研究单位分析几何与应用实验室)
Counterexamples to the Landis conjecture in dimensions three and higher
Ludwig-Maximilians Universität München(慕尼黑路德维希-马克西米利安大学);Munich Center for Quantum Science and Technology(慕尼黑量子科学与技术中心);Caltech(加州理工学院);University of California, Irvine(加州大学尔湾分校)
Quantitative Landis-type result for Dirac operators
BCAM – Basque Center for Applied Mathematics(巴斯克应用数学中心);Ikerbasque, Basque Foundation for Science(伊克拉巴斯科,巴斯克科学基金会);Universidad del País Vasco / Euskal Herriko Unibertsitatea(巴斯克大学)