Iteration-complexity of gradient, subgradient and proximal point methods   on Riemannian manifolds
  This paper considers optimization problems on Riemannian manifolds and analyzes iteration-complexity for gradient and subgradient methods on manifolds with non-negative curvature. By using tools from the Riemannian convex analysis and exploring directly the tangent space of the manifold, we obtain different iteration-complexity bounds for the aforementioned methods, complementing and improving related results. Moreover, we also establish iteration-complexity bound for the proximal point method on Hadamard manifolds. 
G. C. Bento, O. P. Ferreira, J. G. Melo
math.NA