# MA3G6 Commutative Algebra

**Lecturer:** Chunyi Li

**Term(s):** Term 1

**Status for Mathematics students:** List A

**Commitment:** 30 one hour lectures

**Assessment:** 85% 3 hour examination, 15% coursework

**Formal registration prerequisites: **None

**Assumed knowledge: **The ring theory part of the second year Maths core:

MA251 Algebra I: Advanced Linear Algebra:

- Jordan Normal Forms
- Classification of Finitely Generated Abelian Groups

MA249 Algebra ll: Groups and Rings:

- Domains (UFD, PID, ED)
- Chinese Remainder Theorem
- Gauss Lemma

**Useful background: **Besides the general interest in Algebra, the following could be useful:

MA257 Introduction to Number Theory:

- Factorisation
- Divisibility
- Euclidean Algorithm
- Elementary factorization algorithms

MA260 Norms, Metrics and Topologies or MA222 Metric Spaces

**Synergies:** The following modules go well together with Commutative Algebra:

- MA3A6 Algebraic Number Theory
- MA377 Rings and Modules (which concentrates more on non-commutative theory)
- MA3D5 Galois Theory

**Leads to: **The following modules have this module listed as **assumed knowledge** or **useful background:**

- MA4J8 Commutative Algebra II
- MA4A5 Algebraic Geometry
- MA453 Lie Algebras
- MA4M3 Local Fields
- MA4L7 Algebraic Curves

**Content**: Commutative Algebra is the study of commutative rings, and their modules and ideals. This theory has developed over the last 150 years not just as an area of algebra considered for its own sake, but as a tool in the study of two enormously important branches of mathematics: algebraic geometry and algebraic number theory. The unification which results, where the same underlying algebraic structures arise both in geometry and in number theory, has been one of the crowning glories of twentieth century mathematics and still plays an absolutely fundamental role in current work in both these fields.

One simple example of this unification will be familiar already to anyone who has noticed the strong parallels between the ring Z (a Euclidean Domain and hence also a Unique Factorization Domain) and the ring F[X] of polynomials over a field (which has both the same properties). More generally, the rings of algebraic integers which have been studied since the 19th century to solve problems in number theory have parallels in rings of functions on curves in geometry.

While self-contained, this course will also serve as a useful introduction to either algebraic geometry or algebraic number theory.

Topics: GrÃ¶bner bases, modules, localization, integral closure, primary decomposition, valuations and dimension.

**Objectives**: This course will give the student a solid grounding in commutative algebra which is used in both algebraic geometry and number theory.

**Books**: Recommended texts:

M.F. Atiyah, I.G. MacDonald, *Introduction to Commutative Algebra,* Addison-Wesley 1969; reprinted by Perseus 2000. [QA251.3.A8]

D. Eisenbud, *Commutative Algebra with a View Toward Algebraic Geometry,* Springer 1995. [QA251.3.E4]

M. Reid, *Undergraduate Commutative Algebra, *CUP 1995. [QA251.3.R3]

R.Y. Sharp, *Steps in Commutative Algebra,* (2nd ed.) CUP 2000. [QA251.3.S4]

O. Zariski and P. Samuel, *Commutative Algebra,* (Volumes I and II). Springer 1975-6. [QA251.3.Z2]