English

Irrationality of finite logarithms in a congruence-class adèle ring

Number Theory 2026-07-30 v1

Abstract

Finite logarithms of non-zero rational numbers can be defined in the "poor man's ad\`{e}le ring" A{\mathcal A} by Fermat quotients modulo sufficiently large primes. This ring contains Q\mathbb{Q} and outside trivial cases, Matsusaka and Seki have shown that finite logarithms cannot take non-zero rational values in A{\mathcal A}. Furthermore, a theorem of Silverman shows they are not zero, assuming the abcabc-conjecture. We extend these results to primes restricted to arithmetic progressions of the form p1modmp\equiv 1\bmod m by relating Fermat quotients to values of cyclotomic polynomials and their logarithmic derivatives. As an application we show that, subject to the abcabc-conjecture, finite logarithms cannot be quadratic irrational in A{\mathcal A} in an appropriate sense.

Keywords

Cite

@article{arxiv.2607.27774,
  title  = {Irrationality of finite logarithms in a congruence-class adèle ring},
  author = {Daniel Evans},
  journal= {arXiv preprint arXiv:2607.27774},
  year   = {2026}
}