Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Topic: Rigidity of Convex Polytopes
Replies: 6   Last Post: Jun 20, 1994 9:29 AM

 Messages: [ Previous | Next ]
 John Sullivan Posts: 14 Registered: 12/6/04
Rigidity of Convex Polytopes
Posted: Jun 16, 1994 6:51 PM

There's a famous theorem of Cauchy (proving a claim of Euclid it seems)
that two convex polyhedra with the same shape faces, assembled the
same way, are in fact congruent. In other words, if you're building
a polyhedron from its faces, it may be floppy when you're part way through,
but when you finish, it is rigid.

Is the same true in higher dimensions? E.g., in R^4, if I assemble
a convex polytope from certain 3-cells (polyhedra, tetrahedra if you like)
of fixed shape, is the result always rigid?

I assume whatever results there are along these lines fall under
Alexandrov's theory of mixed volumes, etc, for convex polytopes.
Unfortunately, our library only had Alexandrov in Russian, so
I figured I'd ask the net if anyone knows the statement of whatever
analogous theorem there might be in higher dimensions.

Thanks,
John Sullivan

Date Subject Author
6/16/94 John Sullivan
6/16/94 Joseph O'Rourke
6/17/94 John Conway
6/19/94 joe malkevitch
6/19/94 John Conway
6/20/94 John Sullivan
6/20/94 Walter Whiteley