7 research outputs found
Zonotopes, Dicings, and Voronoiâs Conjecture on Parallelohedra
AbstractIn 1909, Voronoi conjectured that if some selection of translates of a polytope forms a facet-to-facet tiling of euclidean space, then the polytope is affinely equivalent to the Voronoi polytope for a lattice. He referred to polytopes with this tiling property as parallelohedra, but they are now frequently called parallelotopes. I show that Voronoiâs conjecture holds for the special case where the parallelotope is a zonotope. I also show that the Voronoi polytope for a lattice is a zonotope if and only if the Delaunay tiling for the lattice is a dicing (defined at the beginning of Section 3)
Extending Torelli map to toroidal compactifications of Siegel space
It has been known since the 1970s that the Torelli map ,
associating to a smooth curve its jacobian, extends to a regular map from the
Deligne-Mumford compactification to the 2nd Voronoi
compactification .
We prove that the extended Torelli map to the perfect cone (1st Voronoi)
compactification is also regular, and moreover
and share a common Zariski open
neighborhood of the image of . We also show that the map to the
Igusa monoidal transform (central cone compactification) is NOT regular for
; this disproves a 1973 conjecture of Namikawa.Comment: To appear in Inventiones Mathematica
Superfluidity of a perfect quantum crystal
In recent years, experimental data were published which point to the
possibility of the existence of superfluidity in solid helium. To investigate
this phenomenon theoretically we employ a hierarchy of equations for reduced
density matrices which describes a quantum system that is in thermodynamic
equilibrium below the Bose-Einstein condensation point, the hierarchy being
obtained earlier by the author. It is shown that the hierarchy admits solutions
relevant to a perfect crystal (immobile) in which there is a frictionless flow
of atoms, which testifies to the possibility of superfluidity in ideal solids.
The solutions are studied with the help of the bifurcation method and some
their peculiarities are found out. Various physical aspects of the problem,
among them experimental ones, are discussed as well.Comment: 24 pages with 2 figures, version accepted for publication in
Eur.Phys.J.