Japanese Journal of Mathematics

, Volume 5, Issue 2, pp 183–189

Generalizations of Arnold’s version of Euler’s theorem for matrices

Authors

    • Department of MathematicsBinghamton University
  • Bogdan V. Petrenko
    • Department of MathematicsSUNY Brockport
Article

DOI: 10.1007/s11537-010-1023-9

Cite this article as:
Mazur, M. & Petrenko, B.V. Jpn. J. Math. (2010) 5: 183. doi:10.1007/s11537-010-1023-9

Abstract.

A recent result, conjectured by Arnold and proved by Zarelua, states that for a prime number p, a positive integer k, and a square matrix A with integral entries one has \({\textrm tr}(A^{p^k}) \equiv {\textrm tr}(A^{p^{k-1}}) ({\textrm mod}{p^k})\). We give a short proof of a more general result, which states that if the characteristic polynomials of two integral matrices AB are congruent modulo pk then the characteristic polynomials of Ap and Bp are congruent modulo pk+1, and then we show that Arnold’s conjecture follows from it easily. Using this result, we prove the following generalization of Euler’s theorem for any 2 × 2 integral matrix A: the characteristic polynomials of AΦ(n) and AΦ(n)-ϕ(n) are congruent modulo n. Here ϕ is the Euler function, \(\prod_{i=1}^{l} p_i^{\alpha_i}\) is a prime factorization of n and \(\Phi(n)=(\phi(n)+\prod_{i=1}^{l} p_i^{\alpha_i-1}(p_i+1))/2\).

Keywords and Phrases:

Euler congruencesEuler’s theoremFermat’s little theoremcongruences for traces

Mathematics Subject Classification (2010):

05A1011A0711C20

Copyright information

© The Mathematical Society of Japan and Springer Japan 2010