Let \(p(k)\) (\(q(k)\)) be the smallest number such that in the projective plane, every simple arrangement of \(n \geq p(k)\) (\( \geq q(k)\)) straight lines (pseudolines) contains \(k\) lines which determine a \(k\)-gonal region. The values \(p(6) = q(6) = 9\) are determined and the existence of \(q(k) (\geq p(k))\) is proved.
Citation
Heiko Harborth, Meinhard Méller. The Esther-Klein-Problem in the Projective Plane[J], Journal of Combinatorial Mathematics and Combinatorial Computing, Volume 015. 171-180. .