64

Questions

9
15
votes
4
answers
959
views

Example of a smooth morphism where you can’t lift a map from a nilpotent thickening?

apr 21 10 at 19:08 Bjorn Poonen 14.2k24775

6
15
votes
8
answers
2k
views

Is every finite-dimensional Lie algebra the Lie algebra of an algebraic group?

may 5 10 at 18:43 Jim Humphreys 26k3782

6
13
votes
12
answers
4k
views

Alternatives to pi day

jul 19 10 at 14:53 Punxas 11

3
13
votes
3
answers
685
views

Can a module be an extension in two really different ways?

oct 18 10 at 1:37 Anton Geraschenko♦♦ 13.7k348108

4
13
votes
1
answer
461
views

Does a degeneration always have a larger-dimensional automorphism group?

mar 14 11 at 10:21 Laurent Moret-Bailly 7,2961929

3
13
votes
0
answers
364
views

Are “fpqc algebraic spaces” algebraic spaces?

oct 9 11 at 0:22 Anton Geraschenko♦♦ 13.7k348108

1
12
votes
2
answers
556
views

If a map restricts to an isomorphism on a closed subscheme and its open complement, must it be an isomorphism?

dec 12 10 at 4:21 Anton Geraschenko♦♦ 13.7k348108

5
12
votes
1
answer
1k
views

How many unit squares can you pack into a rectangle with nearly integer side lengths?

mar 27 10 at 15:01 Anton Petrunin 16.5k41110

8
12
votes
3
answers
3k
views

Finite extension of fields with no primitive element

jun 24 10 at 9:05 Charles Matthews 9,7201239

7
11
votes
3
answers
847
views

Can a coequalizer of schemes fail to be surjective?

apr 3 11 at 19:15 Laurent Moret-Bailly 7,2961929

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