On Kemnitz' Conjecture Concerning Lattice Points in the Plane
  In 1961, P. Erd\H{o}s, A. Ginzburg, and A. Ziv proved a remarkable theorem stating that each set of $2n-1$ integers contains a subset of size $n$, the sum of whose elements is divisible by $n$. We will prove a similar result for pairs of integers, i.e., planar lattice points, usually referred to as Kemnitz' conjecture. 
Christian Reiher
math.NT