Project III (MATH3382) 2023-24


Further Elementary Number Theory

Alexander Stasinski

Description

This project will explore results that build on but go beyond what is covered in Elementary Number Theory II. Several results can be better understood by using a bit of algebra (groups and rings). We start with congruences modulo a power of a prime (Chapter 4 in Jones-Jones) and how this leads to \(p\)-adic numbers. We then study primitive roots from the point of view of generators of groups of the form \((\mathbb{Z}/n)^{\times}\). In ENT II we only have time to prove the existence of primitive roots modulo a prime, but here we will establish precisely for which natural numbers \(n\) a primitive root exists modulo \(n\) (Chapter 6 in Jones-Jones; Chapter 4 in Ireland-Rosen). Similarly, we then study quadratic residues modulo not only a prime, but a power of a prime and, ultimately, and arbitrary integer (Chapter 7 in Jones-Jones).

Further topics for individual study depend on interest, but may include: Further theory of \(p\)-adic numbers, different proofs of quadratic reciprocity (e.g., using group theory), Quadratic Gauss Sums (Chapter 6 in Ireland-Rosen), Equations over Finite Fields (Chapter 10 in Ireland-Rosen).

Prerequisites

Elementary Number Theory II and Algebra II.

Resources

    1. G. A. Jones & J. M. Jones, Elementary Number Theory, 1998.
    2. K. Ireland & M. Rosen, A Classical Introduction to Modern Number Theory, 2nd ed, 1990.

email: Alexander Stasinski


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