Introduction to Algebraic Geometry

Spring 2008

Course number: 22M:330:002 Topics in Algebra

Class meets: TuTh 1:05-2:20pm in 221 MacLean Hall.

Instructor: Julianna Tymoczko
Office: 225G MacLean Hall
Office Phone: 335-0790
email: tymoczko AT math DOT uiowa DOT edu.

Office hours: Monday 10-11:30am, Tuesday 2:30-4pm, and by appointment.

Course homepage: http://www.divms.uiowa.edu/~tymoczko/ag_intro/index.html This webpage will be updated regularly with suggested problems and readings.

Prerequisites: Abstract algebra at the first-year graduate level. Algebraic topology at the first-year graduate level is helpful but not necessary.

Course description: Algebraic geometry has two very different faces. Classical algebraic geometry reached a pinnacle in the Italian school of the late nineteenth century, though it is now experiencing a renaissance. It attacks concrete questions, for instance how many lines there are on a cubic surface, in hands-on ways involving a lot of elbow grease. (By the way, the answer is 27.)

By the turn of the century, these methods had carried algebraic geometry about as far as they could. The twentieth century saw the birth of abstract algebra (groups, rings, modules), which was the key to a new algebraic geometry. In the 1960s, Grothendieck (with others) discovered modern algebraic geometry in schemes. The notion of schemes unifies algebraic geometry and number theory, and is an incredibly powerful tool in contemporary mathematics. For instance, Andrew Wiles's proof of Fermat's Last Theorem used these tools in crucial ways, and modern cryptography is based on algebro-geometric techniques.

This course will present both aspects of algebraic geometry. The first ten weeks will emphasize classical algebraic geometry, including many examples, to develop intuition and give a feel for the field. The last third of the course will discuss schemes, to introduce this transformational concept of modern mathematics.

Goals and objectives: The goal of the course is to give an introduction to the main topics and ideas in contemporary algebraic geometry, including the important questions that are asked in algebraic geometry and the kinds of methods that can be used to solve them. At the end of the semester, a student who bumps into these concepts in his or her research would know what they mean and how to get more information if needed. Students will also gain some practice with the basic tools and techniques of algebraic geometry.

Course work: Regular problem sets will be handed out, on the grounds that math is learned through doing not listening. Each set will be short and will consist of problems geared to consolidate your understanding of the material. No homework will be collected.

Each student will give an in-class presentation about a particular algebraic variety or family of algebraic varieties, selected from the student's research interests or from a list provided by the instructor. Possibilities include Veronese and Segre embeddings, Grassmannians, flag varieties, curves, toric varieties, and Hilbert schemes of points in the plane.

In addition, the students will collectively produce a LaTeXed set of course notes that will be posted on the course webpage. Each student will be responsible for LaTeXing at least one lecture to contribute to the notes. This page has some useful LaTeX links and encouragement.

The presentation, together with class participation, will determine the course grade.

Readings (suggested but not required):

[D] Danilov, Algebraic Varieties and Schemes, in Algebraic Geometry I: Algebraic Curves, Algebraic Manifolds and Schemes (ed. Shafarevich)

[EH] Eisenbud and Harris, The Geometry of Schemes

[GH] Griffiths and Harris, Principles of Algebraic Geometry

[Harr] Harris, Algebraic Geometry: A First Course

[Hart] Hartshorne, Algebraic Geometry

[R] Reid, Undergraduate Algebraic Geometry

[S] Shafarevich, Algebraic Geometry I: Varieties in Projective Space

All readings are on reserve in the Mathematical Sciences Library.

A note to students thinking ahead: Reid's book is a particularly readable introduction to algebraic geometry if you are interested in getting a jumpstart on the course.

Note to student: The Department of Mathematics has offices in 14 MacLean Hall. To make an appointment to speak with the chair of the department, call 335-0714 or contact the Departmental Secretary in 14 MacLean Hall.



Schedule
This syllabus is incomplete and tentative, and will be superseded by later versions as the course evolves.

Week Topics
1 Affine algebraic varieties: first properties
Tuesday, Jan. 22: Varieties and ideals, irreducibility (figures for the notes are here) [Hart pp. 1-5, R pp. 48-57]
Thursday, Jan. 24: Zariski topology and general points, dimension, coordinate rings and regular functions [Hart pp. 6-7, Harr Ch. 11]
2 Affine algebraic varieties: rational functions and creating new varieties
Tuesday, Jan. 29: Regular functions and maps, rational functions and function fields [R pp. 66-77, S 1.2 and 1.3]
Thursday, Jan. 31: Creating new varieties from old: products, intersections, graphs, blow-ups, and fibers [S 2.4, Hart pp. 28-30]
3 Affine algebraic varieties: Differential calculus and sheaves
Tuesday, Feb. 5: Differentials, localization, tangent space/cone, canonical bundle [D pp. 204-210, S 3.5]
Thursday, Feb. 7: Sheaves: definitions and examples [Hart 2.1, EH 11-18]
4 Projective algebraic varieties: First properties
Tuesday, Feb. 12: Definitions and difference from affine varieties, morphisms, gluing, products [R 79-90, Hart 1.2, S 1.5]
Thursday, Feb. 14: Student presentation: Hypersurfaces
5 Degree
Tuesday, Feb. 19: Degree: Bezout's theorem, degree and codimension, Hilbert polynomials [Harr Ch. 18, R pp. 17-18, D pp. 250-255]
Thursday, Feb. 21: Student presentation: Algebraic curves
6 Special morphisms
Tuesday, Feb. 26: Special morphisms: finite, proper, unramified, etale [D pp. 216-226 and 230-235, Harr 177-181]
Thursday, Feb. 28: Student presentation: Veronese and Segre embeddings
7 Divisors
Tuesday, Mar. 4: Divisors: definitions, exceptional divisors, Cartier and Weil divisors [S 3.1 and 3.2, D 255-260]
Thursday, Mar. 6: Student presentation: Toric varieties (or Picard and Jacobian varieties, see below)
8 Algebraic cycles and the Chow ring
Tuesday, Mar. 11: Algebraic cycles, intersection theory for varieties [D 266-276]
Thursday, Mar. 13: Student presentation: Grassmannians
9 Bundles and sections
Tuesday, Mar. 25: Vector bundles on varieties, Coherent sheaves [D 196-202]
Thursday, Mar. 27: Student presentation: Flag varieties
10 Special topics
Tuesday, Apr. 1: Student presentation: Determinantal varieties (or Schubert varieties, Springer fibers, Toric varieties (part II))
Thursday, Apr. 3: Student presentation: Picard and Jacobian varieties (or the parenthetical options above)
11 Introduction to Schemes: First properties
Tuesday, Apr. 8: Affine and projective schemes: basic definitions and properties [EH pp. 7-28, Hart pp. 69-95]
Thursday, Apr. 10: Morphisms, gluing, fibered products [EH pp. 28-47, Hart pp. 69-95]
12 Introduction to Schemes: Examples
Tuesday, Apr. 15: Examples: Reduced and nonreduced schemes, flat families of schemes, arithmetic schemes [EH pp. 47-91]
Thursday, Apr. 17: Student presentation: Conics over Spec Z
13 Proj
Tuesday, Apr. 22: Proj of a graded ring [EH pp. 95-122, Hart pp. 160-169]
Thursday, Apr. 24: Student presentation: Universal hypersurfaces
14 Blow-ups
Tuesday, Apr. 29: Definitions and constructions, examples, blow-ups along nonreduced schemes [EH pp. 162-184, Hart pp. 160-169]
Thursday, May 1: Student presentation: Fano schemes
15 Families of schemes
Tuesday, May 6: Families of schemes: moduli spaces and parameter spaces [EH pp. 259-279, Hart pp. 89-90]
Thursday, May 8: Student presentation: The Hilbert scheme of points in a plane
 


Academic Fraud: Plagiarism and any other activities that result in a student presenting work that is not his or her own are academic fraud. Academic fraud is reported to the departmental DEO and then to the Associate Dean for Academic Programs and Services in the College of Liberal Arts and Sciences. www.clas.uiowa.edu/students/academic_handbook/ix.shtml

Making a Suggestion or a Complaint: Students have the right to make suggestions or complaints and should first visit with the instructor, then with the course supervisor if appropriate and next with the departmental DEO. All complaints must be made within six months of the incident. www.clas.uiowa.edu/students/academic_handbook/ix.shtml#5

Accommodations for Disabilities: A student seeking academic accommodations first must register with Student Disability Services and then meet with a SDS counselor who determines eligibility for services. A student approved for accommodations should meet privately with the course instructor to arrange particular accommodations. See www.uiowa.edu/~sds/

Understanding Sexual Harassment: Sexual harassment subverts the mission of the University and threatens the well-being of students, faculty, and staff. Visit www.sexualharassment.uiowa.edu/ for definitions, assistance, and the full policy.

Reacting Safely to Severe Weather: The University of Iowa Operations Manual section 16.14 outlines appropriate responses to a tornado (i) or to a similar crisis. If a tornado or other severe weather is indicated by the UI outdoor warning system, members of the class should seek shelter in rooms and corridors in the innermost part of a building at the lowest level, staying clear of windows, corridors with windows, or large free-standing expanses such as auditoriums and cafeterias. The class will resume, if possible, after the UI outdoor warning system announces that the severe weather threat has ended.

Administrative Home of the Course: The administrative home of this course is the College of Liberal Arts and Sciences, which governs academic matters relating to the course such as the add / drop deadlines, the second-grade-only option, issues concerning academic fraud or academic probation, and how credits are applied for various CLAS requirements. Please keep in mind that different colleges might have different policies. If you have questions about these or other CLAS policies, visit your academic advisor or 120 Schaeffer Hall and speak with the staff. The CLAS Academic Handbook is another useful source of information on CLAS academic policy: www.clas.uiowa.edu/students/academic_handbook/index.shtml