Martingales in Reductive Homogeneous spaces

The subject of this work is to study martingales in a reductive homogeneous space with respect to a symmetric connection. Our basic idea is to view homogenous spaces as principal fiber bundles and, thus, to study martingales on homogeneous space with aid of horizontal martingales on Lie group. Furthermore, using the stochastic logarithm we give a characterization of martingales on homogenous space. To end, we study the martingales in spheres $S^n$ and $SL(n,\mathbb{R})\mathrm{/}SO(n,\mathbb{R})$, $n\ge 2$.