Is there a set of points such that not all its points are coplanar, no three of the points are collinear, and for any we can find points for which ?
KURSCHAK 2006
Kürschák Competition 2006.
Other problems
Let be positive integers such that . Consider the subsets of whose any two elements differ by at least . Prove that the number of such subsets not containing is at most times the number of those that do contain .
We deal cards in some way to people sitting around a table. From then on, in one move a person with at least cards gives one card to each of his/her neighbors. Prove that eventually a state will be reached where everyone has at most one card.