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Discrete & Computational Geometry

, Volume 15, Issue 4, pp 429–441 | Cite as

McLaren’s improved snub cube and other new spherical designs in three dimensions

  • R. H. Hardin
  • N. J. A. Sloane
Article

Abstract

Evidence is presented to suggest that, in three dimensions, spherical 6-designs withN points exist forN=24, 26,≥28; 7-designs forN=24, 30, 32, 34,≥36; 8-designs forN=36, 40, 42,≥44; 9-designs forN=48, 50, 52,≥54; 10-designs forN=60, 62, ≥64; 11-designs forN=70, 72,≥74; and 12-designs forN=84,≥86. The existence of some of these designs is established analytically, while others are given by very accurate numerical coordinates. The 24-point 7-design was first found by McLaren in 1963, and—although not identified as such by McLaren—consists of the vertices of an “improved” snub cube, obtained from Archimedes' regular snub cube (which is only a 3-design) by slightly shrinking each square face and expanding each triangular face. 5-designs with 23 and 25 points are presented which, taken together with earlier work of Reznick, show that 5 designs exist forN=12, 16, 18, 20,≥22. It is conjectured, albeit with decreasing confidence fort≥9, that these lists oft-designs are complete and that no other exist. One of the constructions gives a sequence of putative sphericalt-designs withN=12m points (m≥2) whereN=1/2t 2(1+o(1)) ast→∞.

Keywords

Discrete Comput Geom Interval Method Triangular Face Soccer Ball Spherical Code 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag New York Inc 1996

Authors and Affiliations

  • R. H. Hardin
    • 1
  • N. J. A. Sloane
    • 1
  1. 1.AT&T Bell LaboratoriesMathematical Sciences Research CenterMurray HillUSA

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