Algebra: An Approach via Module Theory(136 Graduate Texts in Mathematics)

This book is designed as a text for a first-year graduate algebra course. The choice of topics is guided by the underlying theme of modules as a basic unifying concept in mathematics. Beginning with standard topics in groups and ring theory, the authors then develop basic module theory, culminating in the fundamental structure theorem for finitely generated modules over a principal ideal domain. They then treat canonical form theory in linear algebra as an application of this fundamental theorem. Module theory is also used in investigating bilinear, sesquilinear, and quadratic forms. The authors develop some multilinear algebra (Hom and tensor product) and the theory of semisimple rings and modules and apply these results in the final chapter to study group represetations by viewing a representation of a group G over a field F as an F(G)-module. The book emphasizes proofs with a maximum of insight and a minimum of computation in order to promote understanding. However, extensive material on computation (for example, computation of canonical forms) is provided.

Table of Contents:
1 Groups.- 1.1 Definitions and Examples.- 1.2 Subgroups and Cosets.- 1.3 Normal Subgroups, Isomorphism Theorems, and Automorphism Groups.- 1.4 Permutation Representations and the Sylow Theorems.- 1.5 The Symmetric Group and Symmetry Groups.- 1.6 Direct and Semidirect Products.- 1.7 Groups of Low Order.- 1.8 Exercises.- 2 Rings.- 2.1 Definitions and Examples.- 2.2 Ideals, Quotient Rings, and Isomorphism Theorems.- 2.3 Quotient Fields and Localization.- 2.4 Polynomial Rings.- 2.5 Principal Ideal Domains and Euclidean Domains.- 2.6 Unique Factorization Domains.- 2.7 Exercises.- 3 Modules and Vector Spaces.- 3.1 Definitions and Examples.- 3.2 Submodules and Quotient Modules.- 3.3 Direct Sums, Exact Sequences, and Horn.- 3.4 Free Modules.- 3.5 Projective Modules.- 3.6 Free Modules over a PID.- 3.7 Finitely Generated Modules over PIDs.- 3.8 Complemented Submodules.- 3.9 Exercises.- 4 Linear Algebra.- 4.1 Matrix Algebra.- 4.2 Determinants and Linear Equations.- 4.3 Matrix Representation of Homomorphisms.- 4.4 Canonical Form Theory.- 4.5 Computational Examples.- 4.6 Inner Product Spaces and Normal Linear Transformations.- 4.7 Exercises.- 5 Matrices over PIDs.- 5.1 Equivalence and Similarity.- 5.2 Hermite Normal Form.- 5.3 Smith Normal Form.- 5.4 Computational Examples.- 5.5 A Rank Criterion for Similarity.- 5.6 Exercises.- 6 Bilinear and Quadratic Forms.- 6.1 Duality.- 6.2 Bilinear and Sesquilinear Forms.- 6.3 Quadratic Forms.- 6.4 Exercises.- 7 Topics in Module Theory.- 7.1 Simple and Semisimple Rings and Modules.- 7.2 Multilinear Algebra.- 7.3 Exercises.- 8 Group Representations.- 8.1 Examples and General Results.- 8.2 Representations of Abelian Groups.- 8.3 Decomposition of the Regular Representation.- 8.4 Characters.- 8.5 Induced Representations.- 8.6 Permutation Representations.- 8.7 Concluding Remarks.- 8.8 Exercises.- Index of Notation.- Index of Terminology.