User Angelo

118 votes

Examples of interesting false proofs

answered Apr 21, 2012 at 14:38

115 votes

what mistakes did the Italian algebraic geometers actually make?

answered Mar 27, 2010 at 13:21

101 votes

When should a supervisor be a co-author?

answered Mar 4, 2011 at 11:04

68 votes

Accepted

Mathematically mature way to think about Mayer–Vietoris

answered May 1, 2010 at 14:11

47 votes

How to refer to a “theorem” that you have shown to be wrong

answered Apr 5, 2013 at 17:00

43 votes

If you went into a coma now and woke in twenty years time what would be your first post on MO?

answered Jul 10, 2010 at 14:18

40 votes

A book you would like to write

answered Feb 4, 2011 at 11:47

34 votes

Accepted

In what sense is the étale topology equivalent to the Euclidean topology?

answered Apr 5, 2011 at 6:21

33 votes

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Profinite groups as étale fundamental groups

answered Dec 1, 2012 at 11:04

32 votes

$\mathbb{P}^n$ is simply connected

answered Apr 19, 2011 at 18:37

31 votes

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An algebraic vector bundle is trivialized by open sets. How many does one need?

answered Dec 15, 2010 at 19:56

31 votes

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Kunneth formula for sheaf cohomology of varieties

answered Aug 5, 2010 at 20:31

31 votes

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Does a "composite field" always exist?

answered Feb 6, 2012 at 20:34

29 votes

Are non-algebraic stacks useful in algebraic geometry?

answered Oct 4, 2011 at 7:35

28 votes

When and how is it appropriate for an undergraduate to email a professor out of the blue?

answered Aug 5, 2010 at 10:08

28 votes

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Vector bundles on $\mathbb{P}^1\times\mathbb{P}^1$

answered Apr 19, 2010 at 17:40

27 votes

Major mathematical advances past age fifty

answered May 23, 2010 at 7:30

26 votes

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Etale cohomology with coefficients in the integers

answered Dec 27, 2011 at 22:23

25 votes

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Does S^6 have the structure of an algebraic variety?

answered Nov 20, 2011 at 8:34

25 votes

Are all Galois cohomology groups also étale cohomology groups?

answered Jun 19, 2010 at 13:18

25 votes

Categories First Or Categories Last In Basic Algebra?

answered Oct 5, 2010 at 7:34

24 votes

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What are the prime ideals of k[[x,y]]?

answered May 10, 2010 at 12:04

21 votes

A question regarding a claim of V. I. Arnold

answered Apr 8, 2010 at 7:21

21 votes

Varieties as an introduction to algebraic geometry / How do professional algebraic geometers think about varieties

answered Oct 21, 2010 at 8:52

21 votes

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Can curves differentiate vector bundles on P^2?

answered Mar 30, 2011 at 15:10

20 votes

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Qcoh(-) algebraic stack?

answered Jun 18, 2011 at 15:09

20 votes

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isomorphism of abelian varieties

answered Apr 9, 2010 at 3:44

20 votes

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If a tensor product of modules is semi-simple, are the tensor factors semi-simple ?

answered Apr 27, 2010 at 11:19

20 votes

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Splitting principle for holomorphic vector bundles

answered Feb 6, 2012 at 21:36

18 votes

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Stacks determined by their coarse moduli spaces

answered Apr 12, 2010 at 19:26

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266 Answers

Examples of interesting false proofs

what mistakes did the Italian algebraic geometers actually make?

When should a supervisor be a co-author?

Mathematically mature way to think about Mayer–Vietoris

How to refer to a “theorem” that you have shown to be wrong

If you went into a coma now and woke in twenty years time what would be your first post on MO?

A book you would like to write

In what sense is the étale topology equivalent to the Euclidean topology?

Profinite groups as étale fundamental groups

$\mathbb{P}^n$ is simply connected

An algebraic vector bundle is trivialized by open sets. How many does one need?

Kunneth formula for sheaf cohomology of varieties

Does a "composite field" always exist?

Are non-algebraic stacks useful in algebraic geometry?

When and how is it appropriate for an undergraduate to email a professor out of the blue?

Vector bundles on $\mathbb{P}^1\times\mathbb{P}^1$

Major mathematical advances past age fifty

Etale cohomology with coefficients in the integers

Does S^6 have the structure of an algebraic variety?

Are all Galois cohomology groups also étale cohomology groups?

Categories First Or Categories Last In Basic Algebra?

What are the prime ideals of k[[x,y]]?

A question regarding a claim of V. I. Arnold

Varieties as an introduction to algebraic geometry / How do professional algebraic geometers think about varieties

Can curves differentiate vector bundles on P^2?

Qcoh(-) algebraic stack?

isomorphism of abelian varieties

If a tensor product of modules is semi-simple, are the tensor factors semi-simple ?

Splitting principle for holomorphic vector bundles

Stacks determined by their coarse moduli spaces