Abstract of May 12th IMO Seminar by Tamon Stephen.

Colourful Simplical Depth

The simplicial depth of a point p relative to a finite set S in Rd is the number of simplices from S that contain p. This quantity is studied in statistics since the point of maximum depth is a d-dimensional median. By considering a colourful generalization of simplicial depth we improve Barany's lower bound for the depth of the median of n points in Rd, and encounter some nice geometric and algorithmic questions.