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10 votes
2 answers
387 views

What is Kept Fixed for Flexible Spheres

For background to this question much recent exciting related things, see this videotaped lecture by Alexander Gaifullin. Consider a triangulation $K$ of a two-dimensional sphere and consider maps ...
Gil Kalai's user avatar
  • 24.7k
28 votes
5 answers
2k views

Visibility of vertices in polyhedra

Suppose $P$ is a closed polyhedron in space (i.e. a union of polygons which is homeomorphic to $S^2$) and $X$ is an interior point of $P$. Is it true that $X$ can see at least one vertex of $P$? More ...
Mostafa - Free Palestine's user avatar
17 votes
2 answers
982 views

Placing points on a sphere so that no 3 lie close to the same plane

Motivation I am working with arbitrary parallelopiped tilings given by projection from a higher dimensional space. The collection of tiles, and some properties of the higher dimensional space are ...
Edmund Harriss's user avatar
7 votes
3 answers
866 views

Not quite regular polyhedra

Take a naive interpretation of regular polyhedra: All vertices (including epsilon ball) congruent All edges congruent All faces congruent We can now find interesting families by removing one ...
Edmund Harriss's user avatar