@article {IOPORT.01184385, author = {Andrzejak, Artur and Welzl, Emo}, title = {Halving point sets.}, year = {1998}, journal = {Documenta Mathematica}, issn = {1431-0643}, pages = {471-478}, publisher = {Universi\"at Bielefeld, Fakult\"at f\"ur Mathematik, Bielefeld}, abstract = {Given $n$ points in $\Bbb R^d$, a hyperplane is called halving if it has at most $\lfloor n/2 \rfloor$ points on either side. This paper surveys known results about the question: How many partitions of a point set (into the points on one side, on the hyperplane, and on the other side) by halving hyperplanes can be realized by an $n$-point set in $R^d$? This is a special case of the famous $k$-set problem. For the planar case the authors discuss the recent upper bound due to {\it T. Dey} [Discrete Comput. Geom. 19, No. 3, 373-382 (1998; Zbl 0899.68107)] and described the Lov\'asz crossing lemma, a useful result in this topic. The remainder of the paper states the known bounds on the number of $j$-facets and presents connections to other topics in discrete geometry and algorithms. These include the upper bound theorem, $k$-levels and parametric matroid optimization.}, reviewer = {Jesus De Loera (Minneapolis)}, identifier = {01184385}, }