Volume 31 (2023), Issue 2 (Special issue: Euclidean lattices: theory and applications)

Editors: Camilla Hollanti & Lenny Fukshansky

1. Multidimensional integer trigonometry

John Blackman ; James Dolan ; Oleg Karpenkov.
This paper is dedicated to providing an introduction into multidimensional integer trigonometry. We start with an exposition of integer trigonometry in two dimensions, which was introduced in 2008, and use this to generalise these integer trigonometric functions to arbitrary dimension. We then move on to study the basic properties of integer trigonometric functions. We find integer trigonometric relations for transpose and adjacent simplicial cones, and for the cones which generate the same simplices. Additionally, we discuss the relationship between integer trigonometry, the Euclidean algorithm, and continued fractions. Finally, we use adjacent and transpose cones to introduce a notion of best approximations of simplicial cones. In two dimensions, this notion of best approximation coincides with the classical notion of the best approximations of real numbers.

2. On triviality of uniform Diophantine exponents of lattices

Oleg N. German.
In this paper we prove that uniform Diophantine exponents of lattices attain only trivial values.

3. Minkowski's successive minima in convex and discrete geometry

Iskander Aliev ; Martin Henk.
In this short survey we want to present some of the impact of Minkowski's successive minima within Convex and Discrete Geometry. Originally related to the volume of an $o$-symmetric convex body, we point out relations of the successive minima to other functionals, as e.g., the lattice point enumerator or the intrinsic volumes and we present some old and new conjectures about them. Additionally, we discuss an application of successive minima to a version of Siegel's lemma.