2008/03/19 by Christiane Frougny, Frougny, Christiane, Wolfgang Steiner +1
Computer Science · Mathematics · #Algorithms and Data Compression #Coding theory and cryptography #cs.CR #cs.DM #math.NT #semigroups and automata theory
paper · pdf · doi:10.48550/arxiv.0803.2874
arxiv created 2009/01/09 · arxiv updated 2009/12/01
For applications to cryptography, it is important to represent numbers with a small number of non-zero digits (Hamming weight) or with small absolute sum of digits. The problem of finding representations with minimal weight has been solved for integer bases, e.g. by the non-adjacent form in base~2. In this paper, we consider numeration systems with respect to real bases β which are Pisot numbers and prove that the expansions with minimal absolute sum of digits are recognizable by finite automata. When β is the Golden Ratio, the Tribonacci number or the smallest Pisot number, we determine expansions with minimal number of digits ±1 and give explicitely the finite automata recognizing all these expansions. The average weight is lower than for the non-adjacent form.