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Higher Invariants Oberseminar (HIOB)
The Higher Invariants Oberseminar (HIOB) for the winter semester 2015 will study
The Grothendieck-Teichmüller Group
Rather than survey the diverse appearances of the Grothendieck Teichmüller group within different subjects, we will concentrate on understanding two theorems:
I. There is an embedding Gal(Q/Q) —> GT of the absolute Galois group of the rational number field into the Grothendieck-Teichmüller group.
II. The Grothendieck-Teichmüller group is isomorphic to the group of homotopy automorphisms of the profinite completion of the little 2-discs operad.
We plan to spend roughly half of the semester on each of these theorems. There will be a brief interlude between parts I and II explaining the action of GT on the Teichmüller tower of moduli spaces of spheres with marked points, and the role of the braid groups.
Dates and location
Mondays, 14.00--16.00 in M102.
Program
The seminar program is available here.
Talks
If you are interested in giving a talk in this seminar, please select a topic and enter your name in the schedule below:
Date | Title | Speaker | Notes | |
1. | 12.10. | Introduction and overview | John Lind | |
2. | 19.10 | The étale fundamental group | Johannes Sprang | |
3. | 26.10 | Curves and function fields | Alexander Voitovitch | |
4. | 02.11 | Belyi's Theorem I | Koen van Woerden | |
5. | 09.11 | Belyi's Theorem II | Florent Martin | |
6. | 16.11 | Lifting the action of Gal(Q/Q) | Johann Haas | |
7. | 23.11 | The monomorphism Gal(Q/Q) —> GT | Niko Naumann | |
8. | 30.11 | Operads, discs, braids | Tom Fiore | Operads, Discs, Braids I |
9. | 07.12 | [seminar cancelled] | ||
10. | 14.12 | Profinite completion | Oriol Raventós | |
10. | 21.12 | Operads, discs, braids II | Dr. Thomas Fiore | Operads, Discs, Braids II |
12. | 11.01 | GT and the braid groups II | Ulrich Bunke | |
13. | 18.01 | An overview of the proof | Geoffroy Horel | |
14. | 25.01 | Weak operads | Dmitri Pavlov | |
15. | 01.02 | GT = hAUT(E2) | Kim Nguyen |