Noperthedron

4 Preliminaries

TODO: This whole chapter needs organization, it’s just a grab bag of miscellaneous results for now.

4.1 Rupert Sets

Theorem 20 Rupert Polyhedron iff Rupert Set
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The following are equivalent:

  • The convex polyhedron with vertex set \(v\) is Rupert.

  • The convex closure of \(v\) is a Rupert set.

Proof

TODO: import this from the other repo

4.2 Poses

TODO

Theorem 21
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Given a pose with zero offset, there exists a view pose that is equivalent to it.

4.3 Pointsymmetry and Rupertness

Theorem 22
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If a set is point symmetric and convex, then it being Rupert implies it being purely rotationally Rupert.

Proof

TODO: informalize proof

Theorem 23
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Suppose \(S\) is a finite set of points in \(\operatorname{\mathbb {R}}^n\). The radius of the polyhedron \(S\) is \(r\) iff

  • there is a vector \(v \in S\) with \(\| v\| = r\)

  • all vectors \(v \in S\) have \(\| v\| \le r\)

Proof

Immediate from definition.

Theorem 24
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Pointsymmetrization preserves radius.

Proof

Because the reflection of a point about the origin preserves its norm.