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Parallelotope


A parallelotope is the generalization of a parallelogram to n dimensions. Moving a point Pi_0 along a line from an initial point to a final point traces out a line segment Pi_1. When Pi_1 is translated from an initial position to a final position, it traces out a parallelogram Pi_2. When Pi_2 is translated, it traces out a parallelepiped Pi_3. Continuing this construction gives an n-dimensional parallelotope Pi_n. The number N_k of k-dimensional faces of Pi_n is

 N_k=2^(n-k)(n; k),

where (n; k) is a binomial coefficient and k=0, 1, ..., n (Coxeter 1973). These are also the coefficients of (x+2)^n.

Grozev and Nikolov (2026) proved that a parallelotope P subset R^n containing one facet of the unit hypercube [0,1]^n and a vertex on the opposite facet satisfies P+Z^n=R^n. Thus its integer translates cover the entire space. In three dimensions, the same conclusion holds for every parallelepiped containing any five vertices of the unit cube. The covering result yields the sharp pyramid volume bound 1/n for a parallelotope-based pyramid contained in [0,1]^n (Grozev and Nikolov 2026).


See also

Honeycomb, Hypercube, Orthotope, Parallelohedron, Pyramid

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References

Coxeter, H. S. M. Regular Polytopes, 3rd ed. New York: Dover, pp. 122-123, 1973.Grozev, D. and Nikolov, N. "Lattice Coverings by Parallelotopes Containing Cube Vertices." 15 Oct 2026. https://arxiv.org/abs/2610.21572.Klee, V. and Wagon, S. Old and New Unsolved Problems in Plane Geometry and Number Theory. Washington, DC: Math. Assoc. Amer., 1991.Zaks, J. "Neighborly Families of Congruent Convex Polytopes." Amer. Math. Monthly 94, 151-155, 1987.

Referenced on Wolfram|Alpha

Parallelotope

Cite this as:

Weisstein, Eric W. "Parallelotope." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Parallelotope.html

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