Seven mutually touching infinite cylinders

Sándor Bozóki, Tsung Lin Lee, L. Rónyai

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

We solve a problem of Littlewood: there exist seven infinite circular cylinders of unit radius which mutually touch each other. In fact, we exhibit two such sets of cylinders. Our approach is algebraic and uses symbolic and numerical computational techniques. We consider a system of polynomial equations describing the position of the axes of the cylinders in the 3 dimensional space. To have the same number of equations (namely 20) as the number of variables, the angle of the first two cylinders is fixed to 90 degrees, and a small family of direction vectors is left out of consideration. Homotopy continuation method has been applied to solve the system. The number of paths is about 121 billion, it is hopeless to follow them all. However, after checking 80 million paths, two solutions are found. Their validity, i.e., the existence of exact real solutions close to the approximate solutions at hand, was verified with the alphaCertified method as well as by the interval Krawczyk method.

Original languageEnglish
Pages (from-to)87-93
Number of pages7
JournalComputational Geometry: Theory and Applications
Volume48
Issue number2
DOIs
Publication statusPublished - 2015

Fingerprint

Circular cylinders
Polynomials
Homotopy Continuation Method
Interval Methods
Path
Computational Techniques
Polynomial equation
Circular Cylinder
Numerical Techniques
Approximate Solution
Radius
Angle
Unit

Keywords

  • Alpha theory
  • Certified solutions
  • Homotopy method
  • Polynomial system
  • Touching cylinders

ASJC Scopus subject areas

  • Computational Theory and Mathematics
  • Computer Science Applications
  • Computational Mathematics
  • Control and Optimization
  • Geometry and Topology

Cite this

Seven mutually touching infinite cylinders. / Bozóki, Sándor; Lee, Tsung Lin; Rónyai, L.

In: Computational Geometry: Theory and Applications, Vol. 48, No. 2, 2015, p. 87-93.

Research output: Contribution to journalArticle

Bozóki, Sándor ; Lee, Tsung Lin ; Rónyai, L. / Seven mutually touching infinite cylinders. In: Computational Geometry: Theory and Applications. 2015 ; Vol. 48, No. 2. pp. 87-93.
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