### 2021　Special courses on advanced topics in Mathematics J

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Mathematics
Instructor(s)
Kuno Yusuke  Nosaka Takefumi
Course component(s)
Lecture    (ZOOM)
Day/Period(Room No.)
Intensive ()
Group
-
Course number
ZUA.E344
Credits
2
2021
Offered quarter
3Q
Syllabus updated
2021/3/19
Lecture notes updated
-
Language used
Japanese
Access Index

### Course description and aims

This lecture is about a certain (infinite-dimensional) Lie algebra, called the Goldman Lie algebra, which is associated with an oriented surface. This Lie algebra is defined in terms of intersections of curves in the surface, and thus one can think of it as an object in low-dimensional topology. Actually, behind its definition there is a geometrical context related to the moduli space of flat bundles over the surface. In this lecture, I will first explain the definition of the Goldman Lie algebra, and then discuss the following two topics: (1) the description of Dehn twists in terms of the Goldman Lie algebra, and (2) the formality of the Goldman bracket (and the Turaev cobracket).
The aim of this lecture is to explain that the intersections of curves on an oriented surface give rise to interesting algebraic structures, which are useful to the study of self-diffeomorphisms and the mapping class group of the surface.

### Student learning outcomes

・Understand the definition of the Goldman Lie algebra.
・Understand the logarithm of Dehn twists.
・Understand the definition of symplectic expansions.
・Understand the definition of the Turaev cobracket.
・Understand the formality of the Goldman bracket and the Turaev cobracket.

### Keywords

Goldman bracket, Turaev cobracket, Dehn twists, mapping class group

### Competencies that will be developed

 ✔ Specialist skills Intercultural skills Communication skills Critical thinking skills Practical and/or problem-solving skills

### Class flow

This is a standard lecture course. There will be some assignments.

### Course schedule/Required learning

Course schedule Required learning
Class 1 The following topics will be covered. ・The fundamental group and the homology group of sufaces ・The lower central series of a free group of finite rank ・Goldman bracket ・The logarithm of Dehn twists ・Generalized Dehn twits ・Symplectic expansions ・Turaev cobracket ・Formality of the Goldman bracket and the Turaev cobracket Details will be provided during each class session.

None required.

None required.

### Assessment criteria and methods

Assignments (100%).

### Related courses

• MTH.B301 ： Geometry I
• MTH.B302 ： Geometry II
• MTH.B331 ： Geometry III
• MTH.B341 ： Topology

### Prerequisites (i.e., required knowledge, skills, courses, etc.)

To have basic knowledge in the theory of differentiable manifolds.