User Qing Liu - MathOverflow

Qing Liu

Member for 14 years, 2 months
Last seen more than 8 years ago

math.u-bordeaux1.fr/~qliu
Bordeaux

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122 Answers

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45 votes

Definition and meaning of the conductor of an elliptic curve

answered Jan 26, 2010 at 22:50

30 votes

Rings in which every non-unit is a zero divisor

answered Oct 18, 2010 at 20:00

30 votes

Accepted

When does the relative differential $df=0$ imply that $f$ comes from the base?

answered Sep 14, 2011 at 0:16

29 votes

Do all curves have Néron models

answered Oct 24, 2012 at 22:47

29 votes

Noether's normalization lemma over a ring A

answered Oct 18, 2010 at 20:39

29 votes

Accepted

morphism closed + fibres proper => proper?

answered Feb 16, 2010 at 22:53

28 votes

Accepted

Is there a connected non-affine scheme $S$ such that it is the union of rings of integers of number fields?

answered Sep 25, 2011 at 22:15

26 votes

Accepted

A finitely generated $\mathbb{Z}$-algebra that is a field has to be finite

answered Mar 6, 2011 at 0:33

23 votes

Completion of modules of differentials (A strange exercise in Liu's AG textbook)

answered Jan 24, 2010 at 1:34

22 votes

Accepted

Continuity in terms of lines

answered Nov 21, 2010 at 21:01

18 votes

Definition of Chow groups over Spec Z

answered Mar 9, 2010 at 21:49

17 votes

When is an irreducible scheme quasi-compact?

answered Aug 5, 2010 at 17:39

16 votes

Accepted

Picard group of reducible varieties

answered Mar 2, 2011 at 18:47

15 votes

Accepted

Can we always find a curve which doesn't have semi-stable reduction

answered Oct 12, 2011 at 22:30

14 votes

Accepted

When is Br(X) = H^2(X,G_m)?

answered Mar 1, 2010 at 9:52

13 votes

Accepted

Example of inclusion which is not a finite morphism

answered Mar 9, 2010 at 21:54

13 votes

countable union of closed subschemes over uncountable field

answered Aug 27, 2011 at 21:35

13 votes

Accepted

Jacobian criterion for smoothness of schemes

answered Nov 3, 2011 at 20:56

12 votes

henselization and completion

answered Aug 29, 2012 at 23:13

12 votes

Accepted

reduction of elliptic curves

answered Sep 10, 2012 at 8:01

12 votes

When two k-varieties with the same underlying topological spaces isomorphic?

answered Jan 23, 2010 at 22:36

12 votes

Accepted

Restricting finite morphism to finite etale morphim

answered Mar 24, 2011 at 21:09

11 votes

Accepted

Does Zariski's Main Theorem come with a canonical factorization?

answered Feb 21, 2011 at 9:37

11 votes

Are there Néron models over higher dimensional base schemes?

answered Jan 25, 2010 at 22:42

11 votes

Accepted

Embedding of a scheme into a regular scheme

answered Oct 18, 2012 at 7:20

10 votes

Cohen-Macaulay sheaves which are not locally free

answered Sep 7, 2012 at 6:43

10 votes

Accepted

Simply connected quasi-projective varieties in positive characteristic

answered Feb 22, 2010 at 14:43

10 votes

Accepted

Is the tensor product of regular rings still regular

answered Dec 22, 2010 at 15:03

9 votes

Picard group of scheme over DVR

answered Jan 16, 2011 at 0:22

9 votes

Descent of closed subschemes over finite fields

answered Nov 10, 2010 at 23:35

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