Yuji Tachikawa's user avatar
Yuji Tachikawa's user avatar
Yuji Tachikawa's user avatar
Yuji Tachikawa
  • Member for 13 years, 11 months
  • Last seen more than a week ago
33 votes
5 answers
3k views

How can I visualize the nontrivial element of $\pi_4(S^3)$ and $\pi_5(S^3)$ ?

29 votes
3 answers
3k views

Why is a 2d TQFT formulated as a functor?

26 votes
5 answers
10k views

What does the word "symplectic" mean?

22 votes
3 answers
2k views

Number of triples of roots (of a simply-laced root system) which sum to zero

21 votes
3 answers
2k views

When is a coadjoint orbit an integrable system (in a weak sense explained below)?

20 votes
3 answers
676 views

Which elements of $H^2(M,\mathbb{Z}/2)$ are the $w_2(E)$ for a real bundle $E$?

17 votes
1 answer
1k views

How can gauge theory techniques be useful to study when topological manifolds can be triangulated?

17 votes
3 answers
2k views

Is there a "motivic Gromov-Witten invariant"?

17 votes
2 answers
2k views

Virasoro action on the elliptic cohomology

15 votes
2 answers
2k views

Why is Drinfeld's Zastava space called Zastava?

13 votes
3 answers
1k views

Complex structure of the Teichmüller space in terms of Fenchel-Nielsen coordinates

13 votes
1 answer
1k views

How should I formalize that there’s no canonical isomorphism between a finite Abelian group and its Pontryagin dual?

13 votes
3 answers
1k views

Computation of $\pi_4$ of simple Lie groups

12 votes
1 answer
350 views

Unoriented bordism with twisted orientation

12 votes
1 answer
1k views

What is the "symplectic duality" between holomorphic symplectic manifolds? Where can I read more about it?

12 votes
2 answers
3k views

Literature on the Springer resolution

11 votes
1 answer
323 views

$\pi_1$ of the moduli of G-bundles on elliptic curves and the double affine braid group

11 votes
3 answers
882 views

Are the rings $\mathbb{C}[X]/\langle X^2- c \mathrm{Tr}(X) X \rangle$ isomorphic when $c$ ranges over a neighborhood of 0?

11 votes
2 answers
298 views

Spectrum $E$ with $H^\bullet(E,\mathbb{Z}/2)=\mathcal{A}//\mathcal{A}(n)$

10 votes
1 answer
1k views

Du Val singularity of type G=A,D,E and "small" representations of G

10 votes
2 answers
1k views

Hall-Littlewood functions and functions on the nilpotent cone

10 votes
0 answers
637 views

On cyclic homology of Ginzburg's DG algebra

8 votes
1 answer
455 views

Explicit method to compute Macdonald/Koornwinder functions

8 votes
1 answer
737 views

Modular forms over $\mathbb{Z}$ vs modular forms with integral Fourier coefficients

7 votes
0 answers
141 views

Explicit framed null bordism realizing $\eta\nu =0$ in stable homotopy group of spheres

7 votes
1 answer
1k views

Ordinary cohomology groups of $(\mathbb{C}^3\times T^2)/\mathbb{Z}_k$ that I need for my string theory research

7 votes
2 answers
642 views

Value of the Chern-Simons functional for flat connections on $S^3/\Gamma$

7 votes
3 answers
988 views

The relation of nilpotent orbits and simple singularities, for orbits smaller than subregular ones

7 votes
0 answers
400 views

Quantum Drinfeld-Sokolov reduction of a Whittaker module

7 votes
4 answers
2k views

Why does Hom need an identity in the definition of the category?