k-Nearest neighbor density estimation on Riemannian Manifolds
  In this paper, we consider a k-nearest neighbor kernel type estimator when the random variables belong in a Riemannian manifolds. We study asymptotic properties such as the consistency and the asymptotic distribution. A simulation study is also consider to evaluate the performance of the proposal. Finally, to illustrate the potential applications of the proposed estimator, we analyzed two real example where two different manifolds are considered. 
Guillermo Henry, Andr\'es Mu\~noz and Daniela Rodriguez
math.ST stat.TH