XT Chen's user avatar
XT Chen's user avatar
XT Chen's user avatar
XT Chen
  • Member for 3 years, 11 months
  • Last seen this week
  • Peking University, Haidian, Beijing, China
19 votes
2 answers
2k views

Why the sphere spectrum is more correct than $\mathbb{Z}$?

13 votes
0 answers
765 views

Seek for a algebro-geometric proof: the group homomorphism $\mathrm{SL}(2,\mathbb{Z}) \rightarrow \mathrm{SL}(2,\mathbb{Z}/N\mathbb{Z})$ is surjective

10 votes
1 answer
1k views

Is there a strictly increasing differentiable function maps positively measurable set to zero measure set?

5 votes
0 answers
130 views

Concrete computation of pullback of the $D$-module $\mathbb{C}[t,t^{-1}]$

4 votes
3 answers
307 views

Question about an inequality described by matrices

4 votes
1 answer
737 views

A contradiction caused by the Kähler identity and the formal adjoint relation

4 votes
0 answers
77 views

Projective objects in the category of simplicial objects in an abelian category

4 votes
1 answer
265 views

How to understand pushout/pullback in a stable $\infty$-category

3 votes
0 answers
210 views

An algebraic proof: A line bundle on a curve with a connection must be of degree 0

3 votes
1 answer
184 views

Definition of 1st degree obstruction class

3 votes
1 answer
294 views

Pullback of $\mathbb{R}$-Cartier divisors

2 votes
0 answers
190 views

Analytic and algebraic definitions of intersection multiplicity of two complex algebraic curves coincide

2 votes
0 answers
154 views

If $n$ is not a power of 2 then the dual Stiefel-Whitney class $\bar{w}_{n-1} = 0$

2 votes
0 answers
189 views

$G$-torsor over $\mathbb{A}^1_S$ where characteristic of $S$ does not divide $|G|$

2 votes
1 answer
295 views

If $\int_E f = 0$ for all $E$ the translation and dilation of $E_0$ then $f = 0 \text{ } a.e.$

1 vote
0 answers
124 views

Domain of definition of a rational map is determined by several coherent sheaves of ideals

1 vote
0 answers
184 views

Motivic cohomology commutes with field extension

1 vote
0 answers
210 views

Zero in colimit of sheaves category

1 vote
0 answers
73 views

$L^r_M = i_* \circ \hat{L}^{r-1}_M \circ i^*$ by the projection formula and the Poincare duality

1 vote
0 answers
125 views

Understanding sheaves on normalisation of a curve: $v_* \mathcal{O}_{\tilde{C}} / \mathcal{O}_C$

0 votes
1 answer
206 views

Definition of group scheme [closed]

0 votes
0 answers
100 views

A fibration is a map which has the right lifting property with respect to injections that are weak equivalences