Math 272 (fall 2008): Introduction to Riemann Surfaces

Time and Place:

Monday, Wednesday, and Friday 10:20-11:10, room 205 Physics Building.

Instructor: Chad Schoen


1. A basic course in functions of one complex variable (eg. Math 245).
2. Rudiments of basic algebra: groups, groups acting on sets, modules over rings. All this and more is covered in Math 251.
3. Familiarity with algebraic topoology (eg. Math 261). The theory of covering spaces plays an especially important role in the study of Riemann surfaces. Homology is also important as are differential forms. Concurrent enrollment in Math 262 is highly recommended.


Lectures on Riemann Surfaces, by Otto Forster. Some lectures may follow the text rather closely, while others will not. The author indicates that the text can be covered in three semesters. Thus we will not cover the entire text. Instead we will concentrate on those topics which lead to a good understanding of compact Riemann surfaces. Sections of the book where we concentrate our attention: 1, 2, 4, 6, 12-17, 19-21, 24-26, 29, with 25 and 26 only touched upon lightly and 17 presented from quite a different point of view.


Complex manifolds of dimension one; elliptic functions; the basic theorems of Riemann surface theory in the special case of one dimensional complex tori; holomorphic maps between compact Riemann surfaces; maps to projective space; linear systems; embedding criteria; sheaves; differential forms; Cech, De Rham, Dolbeault cohomology; existence of non-constant meromorphic functions on compact Riemann surfaces; Hurwitz formula; Riemann-Roch and Serre Duality; applications of the aforementioned theorems; the Hodge decomposition theorem; the Jacobian variety; the Abel-Jacobi map.

After defining Riemann surfaces we begin the study of complex tori via the theory of elliptic functions. This allows us to give elementary proofs of the main theorems in the subject in the special case of (one dimensional) complex tori. The remainder of the course is devoted to extending these results to the case of arbitrary compact connected Riemann surfaces. For this we introduce and study carefully a number of important technical tools, most prominently sheaves, differential forms and Cech cohomology. Considerable time and effort will be spent acquiring the necessary familiarity with these basic tools before applying them to prove the theorems above.

Relationships with other courses

This is a standard foundational course on a topic of fundamental importance in many areas of mathematics. It supplies important background knowledge for students who intend to write a dissertation with many of the pure mathematicians at Duke. More advanced courses on complex manifolds build directly on this material. The course may be viewed as an introduction to algebraic geometry in the sense that there is a parallel theory of algebraic curves. Several crucial results about algebraic curves are much harder to prove than the analogous results about Riemann surfaces. Thus the study of Riemann surfaces is an important source of intuition in algebraic geometry. Riemann surfaces play a very important role in string theory. There are numerous connections with differential geometry (metrics of constant curvature, minimal surfaces, the Hodge theorem). Finally there are substantial connections to algebraic topology and to number theory. The latter arise in two quite separate ways, one being through the theory of elliptic functions and modular forms, the other via the analogy of number fields to fields of meromorphic functions.

Additional helpful references

Lang, Complex analysis
Lang, Elliptic functions
Miranda, Algebraic Curves and Riemann Surfaces
Gunning, Lectures on Riemann surfaces
Narasimhan, Compact Riemann surfaces
Silverman, Advanced topics in the arithmetic of elliptic curves