A Positive Fraction Erdos - Szekeres Theorem

نویسندگان

  • Imre Bárány
  • Pavel Valtr
چکیده

We prove a fractional version of the Erdős–Szekeres theorem: for any k there is a constant ck > 0 such that any sufficiently large finite set X ⊂ R2 contains k subsets Y1, . . . ,Yk , each of size ≥ ck |X |, such that every set {y1, . . . , yk} with yi ∈ Yi is in convex position. The main tool is a lemma stating that any finite set X ⊂ Rd contains “large” subsets Y1, . . . ,Yk such that all sets {y1, . . . , yk}with yi ∈ Yi have the same geometric (order) type. We also prove several related results (e.g., the positive fraction Radon theorem, the positive fraction Tverberg theorem).

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عنوان ژورنال:
  • Discrete & Computational Geometry

دوره 19  شماره 

صفحات  -

تاریخ انتشار 1998