sorry, just understood the problem.
I am not sure I am posting in the right section so please tell me if I need to move this thread.
I am facing a quite difficult problem. Here it is:
Let us denote by the convex hull of the points .
is the set of extremal points of (ie those at the boundary of the convex hull) and are the indexes of those points.
Finally, we define the correspondence where .
It is only a guess, but I think that equals either , or where index is such that .
If you have any hint on this topic, please let me know !