Unsolved Problem 23:

How should you locate 13 cities on a spherical planet so that the minimum distance between any two of them is as large as possible?


[Meschkowski 1966]
Herbert Meschkowski, Unsolved and Unsolvable Problems in Geometry. Frederick Ungar Publishing Co. New York: 1966. Page 1.
Thirteen Points on a Sphere
Each week, for your edification, we publish a well-known unsolved mathematics problem. These postings are intended to inform you of some of the difficult, yet interesting, problems that mathematicians are investigating. We do not suggest that you tackle these problems, since mathematicians have been unsuccessfully working on these problems for many years.

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