by Achill Schürmann, Frank Vallentin.
Series: 2004-07, Preprints
We describe algorithms which solve two classical problems in lattice geometry for any fixed dimension d: the lattice covering and the simultaneous lattice packing-covering problem. Both algorithms involve semidefinite programming and are based on Voronoi's reduction theory for positive definite quadratic forms which describes all possible Delone triangulations of $Z^d$. Our implementations verify all known results in dimensions $d <= 5$. Beyond that we attain complete lists of all locally optimal solutions for $d = 5$. For
$d = 6$ our computations produce new best known covering as well as packing-covering lattices which are closely related to the lattice $E_6^*$.
lattice, packing, covering, quadratic forms, semidefinite programming