Homological Algebra Notes

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Author(s): Sean Sather-Wagstaff

Language: English
Pages: 233

Introduction September 8, 2009......Page 5
Format of these notes......Page 7
Notation and conventions......Page 8
I.1. Finitely Generated Free Modules......Page 9
I.2. Products of Modules......Page 11
I.3. Coproducts of Modules......Page 13
I.4. Localization......Page 15
I.5. Hom: Functoriality and Localization......Page 18
II.1. Existence and Uniqueness......Page 29
II.2. Functoriality and Base-Change......Page 33
II.3. Commutativity and Associativity......Page 39
II.4. Right-Exactness......Page 43
II.5. Hom-Tensor Adjointness......Page 48
III.1. Injective and Projective Modules......Page 51
III.2. Flat Modules......Page 59
III.3. Faithfully Flat Modules......Page 66
III.4. Power Series Rings......Page 68
III.5. Flat Ring Homomorphisms......Page 73
III.7. Completions: Some Details......Page 77
IV.1. Chain Complexes and Homology......Page 79
IV.2. Resolutions......Page 84
IV.3. Ext-Modules......Page 87
IV.4. Tor-Modules......Page 92
IV.5. Epilogue......Page 94
V.1. Assumptions......Page 97
V.2. Associated Primes and Supports of Modules......Page 99
V.3. Prime Filtrations......Page 104
V.4. Prime Avoidance and Nakayama's Lemma......Page 108
V.5. Regular Sequences and Ext......Page 113
V.6. Four Lemmas......Page 120
VI.1. Chain Maps......Page 123
VI.2. Isomorphisms for Ext and Tor......Page 125
VI.3. Liftings of Resolutions......Page 129
VI.4. Induced Chain Maps......Page 133
VI.5. Ext-maps via projective resolutions......Page 139
VI.6. Ext-maps via injective resolutions......Page 143
VI.7. Tor-maps......Page 145
VII.2. Depth and Dimension......Page 151
VII.3. Ext and Projective Dimension......Page 154
VII.4. Tor and Projective Dimension......Page 160
VII.5. Ext and Injective Dimension......Page 162
VII.6. Tor and Flat Dimension......Page 165
VIII.1. General Long Exact Sequences......Page 169
VIII.2. Long Exact Sequences in Ext and Tor......Page 175
VIII.3. Horseshoe Lemmas......Page 178
VIII.4. Mapping Cones......Page 182
VIII.5. Ext, Tor, and Resolutions......Page 187
VIII.6. Koszul Complexes......Page 191
VIII.7. Epilogue: Tor and Torsion......Page 200
IX.1. Projective Dimension and Regular Sequences......Page 203
IX.2. The Auslander-Buchsbaum Formula......Page 205
IX.3. Depth and Flat Ring Homomorphisms......Page 208
IX.4. Injective Dimension and Regular Sequences......Page 213
X.1. Background from Dimension Theory......Page 215
X.2. Definitions and Basic Properties......Page 217
X.3. Theorems of Auslander, Buchsbaum and Serre......Page 220
X.4. Regularity and Flat Local Homomorphisms......Page 224
Index......Page 227
Bibliography......Page 229