Liouville Theorem for $k-$curvature equation in half space with fully nonlinear boundary condition
Wei Wei
TL;DR
The paper establishes a Liouville-type rigidity result for metrics in the half-space $\\mathbb{R}_{+}^{n}$ with constant $\sigma_{k}$-curvature and a positive constant boundary curvature $\\mathcal{B}_{k}^{g}$, where $\\mathcal{B}_{k}^{g}$ is derived from Chen's variational functional for $\\sigma_{k}(A_{g})$. It develops the boundary linearization, proves ellipticity within the $\\Gamma_{k}^{+}$ cone, and applies the method of moving spheres to obtain an explicit Kelvin-type profile $u(y)=\left(\frac{\sqrt{b}}{1+b|y-p|^{2}}\right)^{\frac{n-2}{2}}$ with corresponding geometric data, plus a corollary in the unit ball. The second part shows that, under a Li-Li-type lifting lemma, the stronger asymptotic assumption holds, enabling the full half-space Liouville theorem. The appendix provides a Corner Hopf Lemma and other technical lemmas to support the boundary analysis. Overall, the work advances the understanding of fully nonlinear boundary conditions for $k$-curvature equations and provides tools for half-space and boundary-constrained problems in conformal geometry.
Abstract
We establish the Liouville theorem for positive constant $σ_{k}$-curvature equation in $\mathbb{R}_{+}^{n}$ and positive constant boundary $\mathcal{B}_{k}^{g}$ curvature equation, where the boundary curvature $\mathcal{B}_{k}^{g}$ is discovered by Sophie Chen \cite{Chen} from the natural variational functional for $σ_{k}(A_{g})$.
