Zobrazeno 1 - 10
of 146
pro vyhledávání: '"Schürmann, Achill"'
Publikováno v:
Communications in Mathematics, Volume 31 (2023), Issue 2 (Special issue: Euclidean lattices: theory and applications) (July 16, 2023) cm:11141
In this paper we give a first study of perfect copositive $n \times n$ matrices. They can be used to find rational certificates for completely positive matrices. We describe similarities and differences to classical perfect, positive definite matrice
Externí odkaz:
http://arxiv.org/abs/2303.17310
Autor:
Schüler, Robert, Schürmann, Achill
We describe a class of combinatorial design problems which typically occur in professional sailing league competitions. We discuss connections to resolvable block designs and equitable coverings and to scheduling problems in operations research. We i
Externí odkaz:
http://arxiv.org/abs/2212.02865
Publikováno v:
Math. Program. 187 (2021), 25-45
In this paper we provide an algorithm, similar to the simplex algorithm, which determines a rational cp-factorization of a given matrix, whenever the matrix allows such a factorization. This algorithm can be used to show that every integral completel
Externí odkaz:
http://arxiv.org/abs/1807.01382
Autor:
Coulangeon, Renaud, Schürmann, Achill
Publikováno v:
Communications in Number Theory and Physics, Volume 15 (2021), Number 3, 489--516
We study the local optimality of periodic point sets in $\mathbb{R}^n$ for energy minimization in the Gaussian core model, that is, for radial pair potential functions $f_c(r)=e^{-c r}$ with $c>0$. By considering suitable parameter spaces for $m$-per
Externí odkaz:
http://arxiv.org/abs/1802.02072
Autor:
Ring, Maren H., Schürmann, Achill
As shown by McMullen in 1983, the coefficients of the Ehrhart polynomial of a lattice polytope can be written as a weighted sum of facial volumes. The weights in such a local formula depend only on the outer normal cones of faces, but are far from be
Externí odkaz:
http://arxiv.org/abs/1709.10390
Autor:
Ladisch, Frieder, Schürmann, Achill
Publikováno v:
SIAM J. Appl. Algebra Geom. 2 (2018), no. 2, pp. 259--280
Let $G$ be a finite permutation group acting on $\mathbb{R}^d$ by permuting coordinates. A core point (for $G$) is an integral vector $z\in \mathbb{Z}^d$ such that the convex hull of the orbit $Gz$ contains no other integral vectors but those in the
Externí odkaz:
http://arxiv.org/abs/1703.01152
Publikováno v:
Linear Algebra and its Applications 523 (2017) 46-51
In this note it is proved that every rational matrix which lies in the interior of the cone of completely positive matrices also has a rational cp-factorization.
Comment: 4 pages, (v2) minor revision, accepted in Linear Algebra and its Applicati
Comment: 4 pages, (v2) minor revision, accepted in Linear Algebra and its Applicati
Externí odkaz:
http://arxiv.org/abs/1701.03148
Publikováno v:
Acta Crystallographica A72 (2016), 673--683
In this paper we report on the full classification of Dirichlet-Voronoi polyhedra and Delaunay subdivisions of five-dimensional translational lattices. We obtain a complete list of $110244$ affine types (L-types) of Delaunay subdivisions and it turns
Externí odkaz:
http://arxiv.org/abs/1507.00238
Autor:
Sikiric, Mathieu Dutour, Gangl, Herbert, Gunnells, Paul E., Hanke, Jonathan, Schuermann, Achill, Yasaki, Dan
In this paper we use topological tools to investigate the structure of the algebraic K-groups K_4 (Z[i]) and K_4 (Z[rho]), where i := sqrt{-1} and rho := (1+sqrt{-3})/2. We exploit the close connection between homology groups of GL_n(R) for n <= 5 an
Externí odkaz:
http://arxiv.org/abs/1411.0584