Azagra Rueda, DanielFerrera Cuesta, JuanSanz Alonso, Beatriz2023-06-202023-06-202008-07-150022-039610.1016/j.jde.2008.03.030https://hdl.handle.net/20.500.14352/49815We prove comparison, uniqueness and existence results for viscosity solutions to a wide class of fully nonlinear second order partial differential equations F(x, u, du, d(2)u) = 0 defined on a finite-dimensional Riemannian manifold M. Finest results (with hypothesis that require the function F to be degenerate elliptic, that is nonincreasing in the second order derivative variable, and uniformly continuous with respect to the variable x) are obtained under the assumption that M has nonnegative sectional curvature, while, if one additionally requires F to depend on d2u in a uniformly continuous manner, then comparison results are established with no restrictive assumptions on curvature.engjournal articlehttp://www.sciencedirect.com/science/article/pii/S0022039608001630restricted access517.95nonsmooth analysisdegenerate elliptic second order PDEsHamilton-Jacobi equationsviscosity solutionRiemannian manifoldEcuaciones diferenciales1202.07 Ecuaciones en Diferencias