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Outline

Upper Bounds for Cyclotomic Numbers

2019, arXiv (Cornell University)

https://doi.org/10.48550/ARXIV.1903.07314

Abstract

Let q be a power of a prime p, let k be a nontrivial divisor of q − 1 and write e = (q − 1)/k. We study upper bounds for cyclotomic numbers (a, b) of order e over the finite field F q. A general result of our study is that (a, b) ≤ 3 for all a, b ∈ Z if p > (√ 14) k/ ord k (p). More conclusive results will be obtained through seperate investigation of the five types of cyclotomic numbers: (0, 0), (0, a), (a, 0), (a, a) and (a, b), where a = b and a, b ∈ {1,. .. , e − 1}. The main idea we use is to transform equations over F q into equations over the field of complex numbers on which we have more information. A major tool for the improvements we obtain over known results is new upper bounds on the norm of cyclotomic integers.

Key takeaways
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  1. The main result states that cyclotomic numbers (a, b) are bounded by 3 given specific conditions on p and k.
  2. Upper bounds for cyclotomic numbers are explored through five types: (0, 0), (0, a), (a, 0), (a, a), and (a, b).
  3. The research focuses on simplifying conditions for p, which is a prime, ensuring manageable upper bounds for cyclotomic numbers.
  4. Improvements over existing results arise from new bounds on the norms of cyclotomic integers and their transformation to complex fields.
  5. The study contributes to the applications of cyclotomic numbers in areas like Jacobi sums and Fermat's Last Theorem.

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