2021/07/29 by Jonas Jankauskas, Jankauskas, Jonas, Jörg Μ. Thuswaldner +1 · 1 citation
Computer Science · Mathematics · #11A63 #11C20 #11H06 #11P21 #15A30 #15B10 #52A40 #90C05 #Coding theory and cryptography #Commutative Algebra (math.AC) #FOS: Mathematics #Number Theory (math.NT) #Polynomial and algebraic computation #Rings, Modules, and Algebras
paper · pdf · doi:10.48550/arxiv.2107.14168
openalex publication_date 2021/07/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Let A be a d × d matrix with rational entries which has no eigenvalue λ∈ ℂ of absolute value |λ| < 1 and let ℤd[A] be the smallest nontrivial A-invariant ℤ-module. We lay down a theoretical framework for the construction of digit systems (A, D), where D⊂ ℤd[A] finite, that admit finite expansions of the form x= d0 + A d1 + ⋯ + Aℓ-1dℓ-1 (ℓ∈ ℕ, d0,…,dℓ-1 ∈ D) for every element x∈ ℤd[A]. We put special emphasis on the explicit computation of small digit sets D that admit this property for a given matrix A, using techniques from matrix theory, convex geometry, and the Smith Normal Form. Moreover, we provide a new proof of general results on this finiteness property and recover analogous finiteness results for digit systems in number fields a unified way.