جبر (متون کارشناسی خالص و کاربردی، 11)

Mark Sepanski's Algebra is a readable introduction to the delightful world of modern algebra. Beginning with concrete examples from the study of integers and modular arithmetic, the text steadily familiarizes the reader with greater levels of abstraction as it moves through the study of groups, rings, and fields. The book is equipped with over 750 exercises suitable for many levels of student ability. There are standard problems, as well as challenging exercises, that introduce students to topics not normally covered in a first course. Difficult problems are broken into manageable subproblems and come equipped with hints when needed. Appropriate for both self-study and the classroom, the material is efficiently arranged so that milestones such as the Sylow theorems and Galois theory can be reached in one semester. Readership: Undergraduate students interested in abstract algebra/modern algebra. Preface xi Chapter 1. Arithmetic 1 1. Integers 1 1.1. Basic Properties 1 1.2. Induction 2 1.3. Division Algorithm 4 1.4. Divisors 5 1.5. Fundamental Theorem of Arithmetic 8 1.6. Exercises 1.1–1.28 9 2. Modular Arithmetic 13 2.1. Congruence 13 2.2. Congruence Classes 14 2.3. Arithmetic 15 2.4. Structure 16 2.5. Applications 20 2.6. Equivalence Relations 24 2.7. Exercises 1.29–1.72 26 Chapter 2. Groups 33 1. Definitions and Examples 33 1.1. Binary Operations 33 1.2. Definition of a Group 34 1.3. Examples 35 1.4. Exercises 2.1–2.29 41 2. Basic Properties and Order 46 2.1. Exercises 2.30–2.52 48 3. Subgroups and Direct Products 51 3.1. Subgroups 51 3.2. Direct Products 54 3.3. Exercises 2.53–2.91 54 4. Morphisms 59 4.1. Introduction 59 4.2. Definitions and Examples 60 4.3. Basic Properties 62 4.4. Exercises 2.92–2.118 63 viiviii CONTENTS 5. Quotients 66 5.1. Definitions 66 5.2. Lagrange’s Theorem 68 5.3. Normality 69 5.4. Direct Products and the Correspondence Theorem 72 5.5. First Isomorphism Theorem 73 5.6. Exercises 2.119–2.169 74 6. Fundamental Theorem of Finite Abelian Groups 81 6.1. Exercises 2.170–2.188 85 7. The Symmetric Group 89 7.1. Cayley’s Theorem 89 7.2. Cyclic Decomposition 90 7.3. Conjugacy Classes 93 7.4. Parity and the Alternating Subgroup 95 7.5. Exercises 2.189–2.229 97 8. Group Actions 103 8.1. Exercises 2.230–2.248 109 9. Sylow Theorems 113 9.1. Exercises 2.249–2.281 118 10. Simple Groups and Composition Series 123 10.1. Simple Groups 123 10.2. Composition Series 126 10.3. Exercises 2.282–2.301 128 Chapter 3. Rings 131 1. Examples and Basic Properties 131 1.1. Definition 131 1.2. Examples 132 1.3. Basic Properties 132 1.4. Subrings 134 1.5. Direct Products 135 1.6. Exercises 3.1–3.39 136 2. Morphisms and Quotients 141 2.1. Morphisms 141 2.2. Ideals 143 2.3. Quotients 144 2.4. Isomorphism Theorem 147 2.5. Exercises 3.40–3.86 147 3. Polynomials and Roots 155 3.1. Division Algorithm 157 3.2. Roots 158 3.3. Rational Root Test 160 3.4. Fundamental Theorem of Algebra 161 3.5. Exercises 3.87–3.129 162CONTENTS ix 4. Polynomials and Irreducibility 169 4.1. Irreducibility 169 4.2. Polynomials over a Field 169 4.3. Exercises 3.130–3.150 172 5. Factorization 174 5.1. Unique Factorization 175 5.2. Quotient Fields 178 5.3. Unique Factorization in Polynomial Rings 179 5.4. Exercises 3.151–3.172 181 6. Principal Ideal and Euclidean Domains 183 6.1. Principal Ideal Domains 183 6.2. Euclidean Domains 184 6.3. Gaussian Integers 185 6.4. Exercises 3.173–3.201 186 Chapter 4. Field Theory 193 1. Finite and Algebraic Extensions 193 1.1. Vector Spaces 193 1.2. Finite and Algebraic Extensions 196 1.3. Exercises 4.1–4.34 200 2. Splitting Fields 204 2.1. Splitting Fields 204 2.2. Algebraic Closures 208 2.3. Exercises 4.35–4.62 211 3. Finite Fields 215 3.1. Exercises 4.63–4.81 217 4. Galois Theory 219 4.1. Galois Groups 219 4.2. Separability 222 4.3. Galois Correspondence 223 4.4. Exercises 4.82—4.135 229 5. Famous Impossibilities 236 5.1. Compass and Straightedge Constructions 236 5.2. Solvability of Polynomials 239 5.3. Exercises 4.136–4.162 243 6. Cyclotomic Fields 245 6.1. Exercises 4.163–4.179 247 Index 251 Sepanski offers an introductory undergraduate algebra text beginning with integers and modular arithmetic and following with group theory, ring theory, and field theory. The final section of the text deals with Sylow's theorems and Galois theory. Included are more than 750 exercises in a range of skill levels including some complex problems rarely seen in first course texts. Annotation 2011 Book News, Inc., Portland, OR (booknews.com) Provides an introduction to the world of modern algebra. Beginning with concrete examples from the study of integers and modular arithmetic, the text steadily familiarises the reader with greater levels of abstraction as it moves through the study of groups, rings, and fields. The book is equipped with over 750 exercises suitable for many levels of student ability.