Useful Links
Mathematics
Number Theory
Algebraic Number Theory
Algebraic Numbers and Integers
Definition and Properties
Algebraic numbers as roots of polynomials with rational coefficients
Distinction between algebraic integers and non-integers
Examples and non-examples of algebraic numbers
Minimal Polynomial
Uniqueness and existence of minimal polynomials
Construction of minimal polynomials
Degree of an algebraic number
Field Extensions
Definition and examples of field extensions
Algebraic extensions versus transcendental extensions
Degree of extensions and the Tower Law
Number Fields
Definition and Examples
Definition of number fields as finite extensions of the rational numbers
Example: Quadratic and cyclotomic fields
Rings of Integers
Definitions and comparison with regular integers
Norm and trace of an algebraic integer
Algebraic integers forming a ring
Dedekind Domains
Definition and properties of Dedekind domains
Role in unique factorization of ideals
Relationship with rings of integers in number fields
Ideals and Factorization
Concepts of Ideals
Definition of prime and maximal ideals
Operations with ideals: sum, product, and intersection
Principal Ideal Domains (PIDs)
Definition and characteristics
Examples within rings of integers
Non-uniqueness of factorization in general integral domains
Unique Factorization of Ideals
Fundamental theorem of ideal theory for Dedekind domains
Contrast with unique factorization of elements
Examples illustrating unique factorization of ideals
Galois Theory and Number Fields
Introduction to Galois Theory
Connection between field extensions and permutation groups
Galois groups and their properties
Applications to Number Theory
Solvability of equations by radicals
Analyzing structure and symmetries of number fields
Kronecker–Weber theorem
Cyclotomic fields as extensions of rational numbers
Class Groups and Class Numbers
Definition of Class Groups
Concept of ideal classes and formation of class group
Class number as a measure of the failure of unique factorization
Computation and Examples
Techniques for computing class numbers
Examples in quadratic fields
Significance in the Study of Number Fields
Role in understanding the arithmetic of the field
Relationship with the distribution of prime ideals
Units in Number Fields
Dirichlet's Unit Theorem
Statement and implications of the theorem
Structure of the group of units in a number field
Calculation Techniques
Finding fundamental units
Examples in quadratic number fields
Applications and Further Insights
Analyses of Pell's equation using units
Connections with algebraic K-theory and regulator elements
2. Analytic Number Theory
First Page
4. Transcendental Number Theory