Spring 2026 Topology Reading Group

We meet in Fine Hall 601. This term's topic is Watanabe's disproof of the Smale conjecture.

Time Speaker Topic References
2:40-4:30 PM, February 18, 2026 Evan An exotic loop of diffeomorphisms of S4 [Wa1], [KL, Lectures 1, 2, and 4]
3:00-5:00 PM, March 18, 2026 Gheehyun Definition and invariance of Watanabe's invariant (TBC) [Wa1], [KL, Lecture 3]
TBD TBD TBD
TBD TBD TBD




References

[Wa1] Tadayuki Watanabe, Exotic elements of the rational homotopy groups of Diff(S2n)

[KL] Danica Kosanović, Jianfeng Lin, Kontsevich invariants from configuration spaces (Lectures 1, 2, 3, 4, and 5)

[Le] Christine Lescop, Knot Invariants and Configuration Space Integrals

[LX] Jianfeng Lin, Yi Xie, Configuration space integrals and formal smooth structures

[Wa2] Tadayuki Watanabe, Some exotic nontrivial elements of the rational homotopy groups of Diff(S4)

[Wa3] Tadayuki Watanabe, Addendum to: Some exotic nontrivial elements of the rational homotopy groups of Diff(S4) (homological interpretation)





















Back to main