Course Identification

Introduction to surface group representations and Higgs bundles

Lecturers and Teaching Assistants

Dr. Roberto Rubio , Prof. Avraham Aizenbud

Course Schedule and Location

First Semester
Sunday, 09:15 - 12:00, Ziskind, Rm 155

Field of Study, Course Type and Credit Points

Mathematics and Computer Science: Lecture; Elective; 3.00 points
Physical Sciences: 2.00 points


Lectures will be given by Roberto Rubio.
The last lecture will take place on: Tuesday 6th February, 13:15-16:00, at Room 155 of the Ziskind building.


Some basic definitions: surface, differentiable manifold, differential forms,complex structure, etc., although we will recall all of them. No previous knowledge on the fundamental group, vector bundles or connections will be assumed.



Language of Instruction


Attendance and participation

Required in at least 80% of the lectures

Grade Type

Pass / Fail

Grade Breakdown (in %)


Evaluation Type


Scheduled date 1


Estimated Weekly Independent Workload (in hours)



The representations of the fundamental group of a closed orientable surface can be understood by means of a manifold (a vector bundle over the surface) together with some extra structure (a flat connection on this bundle). When a complex structure is chosen on the surface, the concept of a Higgs bundle over a Riemann surface arises naturally. The spaces parameterizing these objects, or moduli spaces, are related by the Hitchin-Kobayashi correspondence. The rich geometric structure of the moduli space of Higgs bundles then becomes a powerful tool to study the topology of the moduli space of surface group representations, or character variety. In this introductory course we will cover the following topics:

  • The fundamental group of a surface and its representations.
  • Basics on bundle theory.
  • Local systems and at connections.
  • Higgs bundles on Riemann surfaces.
  • Moduli spaces and the Hitchin{Kobayashi correspondence.
  • The geometry of the moduli space of Higgs bundles and the topology of the character variety.

An overview of the course will be given at the beginning of the rst class. The rest three weeks will cover the background material. From the fourth week, each weekly class will consist of three parts:

  • A 45min survey lecture.
  • A 90min hands-on working session.
  • A 30min student-directed working session.

Those interested in knowing about this subject are most welcome to attend only the rest part of the class from the fourth week. Those interested in a deep understanding and working knowledge can attend the other parts. Officially registered students are expected to attend and participate in most of the classes.

Learning Outcomes

Upon successful completion of this course, students should be able to:

  1. Achieve a working knowledge of concepts such as associated bundles, cross sections, connections, etc.
  2. Demonstrate knowledge of the basics about the Hitchin-Kobayashi correspondence and the concepts appearing in it.
  3. Demonstrate acquaintance with an example of the powerful interactions between different fields, namely, geometry into topology and representation theory.
  4. independently read relevant literature on the topic.

Reading List