Displaying similar documents to “Improvement of inequalities for the ( r , q ) -structures and some geometrical connections”

On stabbing triangles by lines in 3-space

Boris Aronov, Jiří Matoušek (1995)

Commentationes Mathematicae Universitatis Carolinae

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We give an example of a set P of 3 n points in 3 such that, for any partition of P into triples, there exists a line stabbing Ω ( n ) of the triangles determined by the triples.

Incidence structures of type ( p , n )

František Machala (2003)

Czechoslovak Mathematical Journal

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Every incidence structure 𝒥 (understood as a triple of sets ( G , M , I ) , I G × M ) admits for every positive integer p an incidence structure 𝒥 p = ( G p , M p , I p ) where G p ( M p ) consists of all independent p -element subsets in G ( M ) and I p is determined by some bijections. In the paper such incidence structures 𝒥 are investigated the 𝒥 p ’s of which have their incidence graphs of the simple join form. Some concrete illustrations are included with small sets G and M .

On Mazurkiewicz sets

Marta N. Charatonik, Włodzimierz J. Charatonik (2000)

Commentationes Mathematicae Universitatis Carolinae

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A Mazurkiewicz set M is a subset of a plane with the property that each straight line intersects M in exactly two points. We modify the original construction to obtain a Mazurkiewicz set which does not contain vertices of an equilateral triangle or a square. This answers some questions by L.D. Loveland and S.M. Loveland. We also use similar methods to construct a bounded noncompact, nonconnected generalized Mazurkiewicz set.