157 research outputs found
Properties of parallelotopes equivalent to Voronoi's conjecture
A parallelotope is a polytope whose translation copies fill space without
gaps and intersections by interior points. Voronoi conjectured that each
parallelotope is an affine image of the Dirichlet domain of a lattice, which is
a Voronoi polytope. We give several properties of a parallelotope and prove
that each of them is equivalent to it is an affine image of a Voronoi polytope.Comment: 18 pages (submitted
Clusters of Cycles
A {\it cluster of cycles} (or {\it -polycycle}) is a simple planar
2--co nnected finite or countable graph of girth and maximal
vertex-degree , which admits {\it -polycyclic realization} on the
plane, denote it by , i.e. such that: (i) all interior vertices are of
degree , (ii) all interior faces (denote their number by ) are
combinatorial -gons and (implied by (i), (ii)) (iii) all vertices, edges and
interior faces form a cell-complex.
An example of -polycycle is the skeleton of , i.e. of the
-valent partition of the sphere , Euclidean plane or hyperbolic
plane by regular -gons. Call {\it spheric} pairs
; for those five pairs is
without the exterior face; otherwise .
We give here a compact survey of results on -polycycles.Comment: 21. to in appear in Journal of Geometry and Physic
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