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A Class of Star-Shaped Bodies

Published online by Cambridge University Press:  20 November 2018

Z.A. Melzak*
Affiliation:
McGill University
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The more important properties of the class κ of all bounded convex bodies in E3 with non-empty interior include: uniform approximability by polyhedra, existence of volume and surface area, and Blaschke's selection principle, [l ], [2 ]. In this note we define and consider a class ℋ of star-shaped bodies in E3, which enjoys many properties of κ, among them the above-mentioned ones, and is considerably larger. Roughly speaking, ℋ consists of closed bounded sets in E3 with nonempty interior, whose boundary is completely visible from every point of a set with non-empty interior. It turns out that ℋ is identifiable with the class of all real-valued positive functions on the sphere S3 which satisfy a Lipschitz condition.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 1959

References

1. Bonnesen, T. and Fenchel, W., Konvexe Koerper, (Chelsea, 1948).Google Scholar
2. Blaschke, W., Kreis und Kugel, (Chelsea, 1949).Google Scholar
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4. Rado, T., Flaechenmass rectifizierbarer Flaechen, Math. Annalen 100 (1928), 445.Google Scholar