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JOURNALS // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika // Archive

Vestnik Moskov. Univ. Ser. 1. Mat. Mekh., 2010 Number 5, Pages 32–36 (Mi vmumm812)

This article is cited in 2 papers

Mathematics

Into how many regions do $n$ lines divide the plane if at most $n-k$ of them are concurrent?

I. N. Shnurnikov

Lomonosov Moscow State University, Faculty of Mechanics and Mathematics

Abstract: A number of connective components of the real projective plane, disjoint with the family of $n\geq 2$ distinct lines is estimated provided at most $n-k$ lines are concurrent. If $n\geq\frac{k^2+k}2+3$, then the number of regions is at least $(k+1)(n-k)$. Thus, a new proof of Martinov's theorem is obtained. This theorem determines all pairs of integers $(n,f)$ such that there is an arrangement of $n$ lines dividing the projective plane into $f$ regions.

Key words: arrangements of lines, polygonal decompositions of projective plane.

UDC: 514.144.12+514.752.5+514.753.25

Received: 19.02.2010



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