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arXiv 2410.02418math.NT
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使用对乘法封闭的数字集的高斯整数与爱森斯坦整数的最优表示

Optimal Representations of Gaussian and Eisenstein Integers using digit sets closed under multiplication

Adam Blažek, Edita Pelantová, Milena Svobodová

AI总结:

本文研究高斯整数和爱森斯坦整数在特定基与数字集下的最优表示,给出最优表示个数的上界并刻画达到上界的整数,推广了有符号二进制记数系统的相关结果。

摘要:

我们研究两种位置记数系统,它们以允许复数的高效加法和乘法而闻名。第一种系统使用基 $\beta = \imath - 1$ 和数字集 $\mathcal{D} = \{ 0, \pm 1, \pm \imath \}$。在该记数系统中,每个非零高斯整数 $x$ 都有无限多个表示。我们关注 $x$ 的最优表示——即非零数字个数尽可能少的表示。$x$ 的其中一个最优表示具有所谓的 $3$-非相邻形式($3$-NAF)。我们给出了 $x$ 的不同最优表示个数的上界,该上界依赖于 $x$ 的 $3$-NAF 中非零数字的个数。我们还刻画了使该上界达到的高斯整数。对于第二种记数系统,我们也回答了同样的问题,该系统使用基 $\beta = \omega - 1$ 和数字集 $\mathcal{D} = \{ 0, \pm 1, \pm \omega, \pm \omega^2 \}$,其中 $\omega = \exp(2\pi\imath / 3)$。在该系统中,每个爱森斯坦整数都有一个 $2$-NAF,并且它是最优的。本文可以理解为 Grabner 和 Heuberger 针对有符号二进制记数系统所得结果的类比,该系统使用基 $\beta = 2$ 和数字集 $\mathcal{D} = \{0, \pm 1\}$。

英文摘要:

We study two positional numeration systems which are known for allowing very efficient addition and multiplication of complex numbers. The first one uses the base $β= \imath - 1$ and the digit set $\mathcal{D} = \{ 0, \pm 1, \pm \imath \}$. In this numeration system, every non-zero Gaussian integer~$x$ has an infinite number of representations. We focus on optimal representations of~$x$ -- i.e., representations with minimal possible number of non-zero digits. One of the optimal representations of~$x$ has the so-called $3$-non-adjacent form ($3$-NAF). We provide an upper bound on the number of distinct optimal representations of~$x$, depending on the number of non-zero digits in the $3$-NAF of~$x$. We also characterize the Gaussian integers for which the upper bound is attained. The same questions are answered also for the second numeration system with base $β= ω- 1$ and digit set $\mathcal{D} = \{ 0, \pm 1, \pm ω, \pm ω^2 \}$, where $ω= \exp(2π\imath / 3)$. In this system, every Eisenstein integer has a $2$-NAF, which is optimal. This paper can be understood as an analogy to the result of Grabner and Heuberger obtained for the signed binary numeration system, using base $β= 2$ and digit set $\mathcal{D} = \{0, \pm 1\}$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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