This book gives an account of recent developments on the interplay between theoretical aspects of commutative algebra and algebraic geometry and computational issues in algebra. A great deal of emphasis is given to the fact that the non-elementary complexity of the underlying fundamental algorithms and data structures (e.g. factorization, Gröbner bases, matrices with polynomial entries) require that the cost of computation be borne largely by theoretical means. The material is focused on the explicit construction of basic objects of algebrogeometric interest - primary decomposition, integral closure, computation of ideal transforms and cohomology, among others. It looks also at various numerical signatures of rings and modules such as those obtained from their Hilbert functions. Another feature is an analysis of nonlinear systems of polynomial equations with the view as to how best deliver the equations to numerical solvers. There are numerous pointers to the current literature, which together with the exercises and a selected set of challenge questions round the text. From the reviews of the hardcover edition: ". Many parts of the book can be read by anyone with a basic abstract algebra course. It seems to the reviewer that it was one of the author's intentions to equip students who are interested in computational problems with the necessary algebraic background in pure mathematics and to encourage them to do further research in commutative algebra and algebraic geometry. But researchers will also benefit from this exposition. They will find an up-to-date description of the related research. The reviewer recommends the book to anybody who is interested in commutative algebra and algebraic geometry and its computational aspects." (P.Schenzel, Mathematical Reviews 2002)

Fundamental Algorithms.- Toolkit.- Principles of Primary Decomposition.- Computing in Artin Algebras.- Nullstellensätze.- Integral Closure.- Ideal Transforms and Rings of Invariants.- Computation of Cohomology (by David Eisenbud).- Degrees of Complexity of a Graded Module.- Appendix A. A Primer on Commutative Algebra.- Appendix B. Hilbert Functions (by Jürgen Herzog).- Appendix C. Using Macaulay 2 (by David Eisenbud, Daniel Grayson and Michael Stillman).- Bibliography.- Index.

Inhaltsangabe1 Fundamental Algorithms.- 1.1 Gröbner Basics.- 1.2 Division Algorithms.- 1.3 Computation of Syzygies.- 1.4 Hilbert Functions.- 1.5 Computer Algebra Systems.- 2 Toolkit.- 2.1 Elimination Techniques.- 2.2 Rings of Endomorphisms.- 2.3 Noether Normalization.- 2.4 Fitting Ideals.- 2.5 Finite and Quasi-Finite Morphisms.- 2.6 Flat Morphisms.- 2.7 Cohen-Macaulay Algebras.- 3 Principles of Primary Decomposition.- 3.1 Associated Primes and Irreducible Decomposition.- 3.2 Equidimensional Decomposition of an Ideal.- 3.3 Equidimensional Decomposition Without Exts.- 3.4 Mixed Primary Decomposition.- 3.5 Elements of Factorizers.- 4 Computing in Artin Algebras.- 4.1 Structure of Artin Algebras.- 4.2 Zero-Dimensional Ideals.- 4.3 Idempotents versus Primary Decomposition.- 4.4 Decomposition via Sampling.- 4.5 Root Finders.- 5 Nullstellensätze.- 5.1 Radicals via Elimination.- 5.2 Modules of Differentials and Jacobian Ideals.- 5.3 Generic Socles.- 5.4 Explicit Nullstellensätze.- 5.5 Finding Regular Sequences.- 5.6 Top Radical and Upper Jacobians.- 6 Integral Closure.- 6.1 Integrally Closed Rings.- 6.2 Multiplication Rings.- 6.3 S2-ification of an Affine Ring.- 6.4 Desingularization in Codimension One.- 6.5 Discriminants and Multipliers.- 6.6 Integral Closure of an Ideal.- 6.7 Integral Closure of a Morphism.- 7 Ideal Transforms and Rings of Invariants.- 7.1 Divisorial Properties of Ideal Transforms.- 7.2 Equations of Blowup Algebras.- 7.3 Subrings.- 7.4 Rings of Invariants.- 8 Computation of Cohomology.- 8.1 Eyeballing.- 8.2 Local Duality.- 8.3 Approximation.- 9 Degrees of Complexity of a Graded Module.- 9.1 Degrees of Modules.- 9.2 Index of Nilpotency.- 9.3 Qualitative Aspects of Noether Normalization.- 9.4 Homological Degrees of a Module.- 9.5 Complexity Bounds in Local Rings.- A A Primer on Commutative Algebra.- A.1 Noetherian Rings.- A.2 Krull Dimension.- A.3 Graded Algebras.- A.4 Integral Extensions.- A.5 Finitely Generated Algebras over Fields.- A.6 The Method of Syzygies.- A.7 Cohen-Macaulay Rings and Modules.- A.8 Local Cohomology.- A.9 Linkage Theory.- B Hilbert Functions.- G-Graded Rings and G-Filtrations.- B.2 The Study ofRvia grF(R).- B.3 The Hilbert-Samuel Function.- B.4 Hilbert Functions, Resolutions and Local Cohomology.- B.5 Lexsegment Ideals and Macaulay Theorem.- B.6 The Theorems of Green and Gotzmann.- C Using Macaulay 2.- C.1 Elementary Uses of Macaulay 2.- C.2 Local Cohomology of Graded Modules.- C.3 Cohomology of a Coherent Sheaf.- References.