Number Theory I Autumn 2023

Lecturer
Richard Pink
Contact for questions regarding content
Lectures
Wed 08:15-10:00, ML E 12
Fr 10:15-11:00, HG D 7.1
Coordinator
Tim Gehrunger
Contact for questions regarding exercise sheets or sessions
Exercise session
Fr 11:15-12:00, HG D 7.1

This course gives an introduction to the theory of number fields, which are fundamental objects in algebraic number theory. Specific topics are: Algebraic integers, discriminant, ideal class group, Minkowski's theorem on the finiteness of the ideal class group, Dirichlet's unit theorem, Dirichlet L-series, zeta function, prime number theorem (+ other material if time permits). Prerequisites are the material on rings, fields, and Galois theory from the courses Algebra I and II (lecture summary in German here)

Exercises

The new exercise sheet will usually be posted here on Thursdays. In the exercise session, we will discuss the exercise sheet of the prior week.

Exercise sheet Solutions
Sheet 1 Solutions 1
Sheet 2 Solutions 2
Sheet 3 Solutions 3
Sheet 4 Solutions 4
Sheet 5 Solutions 5
Sheet 6 Solutions 6
Sheet 7 Solutions 7
Sheet 8 Solutions 8
Sheet 9 Solutions 9
Sheet 10 Solutions 10
Sheet 11 Solutions 11
Sheet 12 Solutions 12
Sheet 13 Solutions 13
Additional Problems Solutions

Content

The lecture course will be recorded but not live streamed. The recordings are here. The screen notes of the lectures are accessible in the list below. There will be a summary of the whole lecture course containing all definitions and theorems but no explanations or proofs. Please send mistakes and improvements to Prof. Pink.

Date Notes Contents
Wednesday, September 20 §1.1-1.2 Integral ring extensions, prime ideals
Friday, September 22 §1.3-1.7 Normalization, localization, field extensions, norm and trace, discriminant
Wednesday, September 27 §1.7-1.10 Discriminant, linearly disjoint extensions, Dedekind rings, fractional ideals
Friday, September 29 §1.10 Discriminant, linearly disjoint extensions, Dedekind rings, fractional ideals
Wednesday, October 4 §1.10-2.1 Fractional ideals, ideals, ideal class group, lattices
Friday, October 6 §2.1-2.3 Lattices, volume, lattice point theorem
Wednesday, October 11 §3.1-3.5 Number fields, absolute discriminant, absolute norm, real and complex embeddings, quadratic number fields
Friday, October 13 §3.5-3.6 Quadratic number fields, cyclotomic fields
Wednesday, October 18 §3.6-3.7 Cyclotomic fields, Quadratic Reciprocity
Friday, October 20 §3.7-4.2 Quadratic Reciprocity, Euclidean embedding, lattice bounds
Wednesday, October 25 §4.2-4.4 Lattice bounds, finiteness of the class group, discriminant bounds
Friday, October 27 §4.4 Discriminant bounds
Wednesday, November 1 §5.1-5.4 Roots of unity, units, Dirichlet’s unit theorem, the real quadratic case
Friday, November 3 §5.3 Dirichlet’s unit theorem
Wednesday, November 8 §6.1-6.2 Modules over Dedekind rings, decomposition of prime ideals
Friday, November 10 §6.2-6.3 Decomposition of prime ideals, decomposition group
Wednesday, November 15 §6.4-6.5 Inertia group, Frobenius
Friday, November 17 §6.6 Relative norm
Wednesday, November 22 §6.6-6.7 Relative norm, different
Friday, November 24 §6.7-6.8 Different, relative discriminant
Wednesday, November 29 §6.8,7.1-7.3 Relative discriminant, Riemann zeta function, Dedekind zeta function, analytic class number formula
Friday, December 01 §7.2 Dedekind zeta function
Wednesday, December 06 §7.2 Dedekind zeta function
Friday, December 08 §7.4 Dirichlet density
Wednesday, December 13 §7.5-7.6 Primes of absolute degree 1, Dirichlet L-series
Friday, December 15 §7.6-7.7 Dirichlet L-series, Primes in arithmetic Progression
Wednesday, December 20 §7.8-7.9 Bonus material: Abelian Artin L-functions, Cebotarev density theorem
Friday, December 22 §7.9 Bonus material: Cebotarev density theorem

You can find the blank slides to fill in your own notes during the lectures here.

Literature