# Foundations of Galois Theory

## 1st Edition

**Authors:**M.M. Postnikov

**Editors:**I. N. Sneddon M. Stark S. Ulam

**eBook ISBN:**9781483156477

**Imprint:**Pergamon

**Published Date:**1st January 1962

**Page Count:**122

**View all volumes in this series:**International Series in Pure and Applied Mathematics

## Table of Contents

Foreword

Preface

I. The Elements of Galois Theory

1. The Elements of Field Theory

1. Preliminary Remarks

2. Some Important Types of Extensions

3. The Minimal Polynomial. The Structure of Simple Algebraic Extensions

4. The Algebraic Nature of Finite Extensions

5. The Structure of Composite Algebraic Extensions

6. Composite Finite Extensions

7. The Theorem That a Composite Algebraic Extension is Simple

8. The Field of Algebraic Numbers

9. The Composition of Fields

2. Necessary Facts from the Theory of Groups

1. The Definition of a Group

2. Subgroups, Normal Divisors and Factor Groups

3. Homomorphic Mappings

3. Galois Theory

1. Normal Extensions

2. Automorphisms of Fields. The Galois Group

3. The Order of the Galois Group

4. The Galois Correspondence

5. A Theorem About Conjugate Elements

6. The Galois Group of a Normal Subfield

7. The Galois Group of the Composition of Two Fields

II. The Solution of Equations by Radicals

1. Additional Facts from the General Theory of Groups

1. A Generalization of the Homomorphism Theorem

2. Normal Series

3. Cyclic Groups

4. Solvable and Abelian Groups

2. Equations Solvable by Radicals

1. Simple Radical Extensions

2. Cyclic Extensions

3. Radical Extensions

4. Normal Fields with Solvable Galois Group

5. Equations Solvable by Radicals

3. The Construction of Equations Solvable by Radicals

1. The Galois Group of an Equation as a Group of Permutations

2. The Factorization of Permutations into the Product of Cycles

3. Even Permutations. The Alternating Group

4. The Structure of the Alternating and Symmetric Groups

5. An Example of an Equation with Galois Group The Symmetric Group

6. A Discussion of the Results Obtained

4. The Unsolvability by Radicals of the General Equation of Degree N ≥ 5

1. The Field of Formal Power Series

2. The Field of Fractional Power Series

3. The Galois Group of the General Equation of Degree N

4. The Solution of Equations of Low Degree

## Description

Foundations of Galois Theory is an introduction to group theory, field theory, and the basic concepts of abstract algebra.

The text is divided into two parts. Part I presents the elements of Galois Theory, in which chapters are devoted to the presentation of the elements of field theory, facts from the theory of groups, and the applications of Galois Theory. Part II focuses on the development of general Galois Theory and its use in the solution of equations by radicals. Equations that are solvable by radicals; the construction of equations solvable by radicals; and the unsolvability by radicals of the general equation of degree n ? 5 are discussed as well.
Mathematicians, physicists, researchers, and students of mathematics will find this book highly useful.

## Details

- No. of pages:
- 122

- Language:
- English

- Copyright:
- © Pergamon 1962

- Published:
- 1st January 1962

- Imprint:
- Pergamon

- eBook ISBN:
- 9781483156477