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The Esther-Klein-Problem in the Projective Plane

Heiko Harborth1, Meinhard Méller1
1Discrete Mathematik Technische Universitat Braunschweig D-38106 Braunschweig, Germany

Abstract

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.