Caps in $\mathbf{\mathbb{Z}_n^2}$
  We consider point sets in $\mathbb{Z}_n^2$ where no three points are on a line - also called caps or arcs. For the determination of caps with maximum cardinality and complete caps with minimum cardinality we provide integer linear programming formulations and identify some values for small $n$. 
Sascha Kurz
math.CO