A lattice is a finitely generated discrete subgroup of Euclidean space. Lattices are an important algorithmic tool in number theory, integral representation theory, geometry, information theory, cryptography, crystallography and have various other applications within mathematics and beyond. Any lattice has only finitely many vectors of a given length, they form the layers of the lattice, which are finite subsets of spheres in the underlying Euclidean space. © 2010 Springer-Verlag Berlin Heidelberg.
Nebe, G. (2010). Lattices and spherical designs. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 6197 LNCS, pp. 4–5). https://doi.org/10.1007/978-3-642-14518-6_4