User Zhen Lin - Mathematics Stack Exchange

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4

27

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0

answers

1

kviews

Simplicial homology of real projective space by Mayer-Vietoris

mar 14 '11 at 21:18 Zhen Lin 20.9k

21

25

votes

1

answer

1

kviews

Sheaf cohomology: what is it and where can I learn it?

reference-request algebraic-topology algebraic-geometry soft-question sheaf-theory

jul 31 '11 at 15:55 Akhil Mathew 16.2k

5

18

votes

2

answers

362

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What is the coproduct of fields, when it exists?

commutative-algebra ring-theory field-theory category-theory

may 17 '12 at 12:46 Matt E 58k

5

17

votes

4

answers

758

views

Proving the snake lemma without a diagram chase

commutative-algebra category-theory homological-algebra abelian-categories

mar 10 at 2:39 Mozibur Ullah 784

12

16

votes

1

answer

994

views

What concept does an open set axiomatise?

general-topology math-history

jul 11 '11 at 1:45 Qiaochu Yuan 117k

3

12

votes

3

answers

1

kviews

The Laplace transform of the first hitting time of Brownian motion

measure-theory probability-theory stochastic-processes martingales brownian-motion

may 19 '12 at 13:53 Did 103k

3

12

votes

1

answer

2

kviews

The cardinality of a countable union of countable sets, without the axiom of choice

homework set-theory cardinals axiom-of-choice ordinals

jan 3 '11 at 17:15 Andres Caicedo 24.4k

4

11

votes

1

answer

638

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Strong and weak convergence in $\ell^1$

functional-analysis convergence banach-spaces lp-spaces weak-convergence

feb 14 at 12:21 Davide Giraudo 56.2k

2

11

votes

0

answers

183

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Model existence for infinitary logics

logic set-theory model-theory

dec 14 at 2:58 Popopo 609

2

11

votes

2

answers

255

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The bijection between homogeneous prime ideals of $S_f$ and prime ideals of $(S_f)_0$

algebraic-geometry commutative-algebra

may 30 '12 at 12:07 Zhen Lin 20.9k

1

9

votes

2

answers

121

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Is a divisor in the hyperplane class necessarily a hyperplane divisor?

algebraic-geometry algebraic-curves projective-geometry

may 8 at 11:21 Georges Elencwajg 44.8k

3

9

votes

3

answers

2

kviews

When does pointwise convergence imply uniform convergence?

real-analysis functional-analysis

may 1 at 8:01 chandmoon 1

9

votes

0

answers

230

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Non-axiomatisability and ultraproducts

logic model-theory

sep 4 at 0:11 Trevor Wilson 5,510

1

9

votes

1

answer

248

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Pullbacks of categories

reference-request category-theory higher-category-theory

jul 11 at 18:02 Mockup 567

7

9

votes

5

answers

915

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Examples of surjective sheaf morphisms which are not surjective on sections

sheaf-theory

aug 18 '11 at 16:19 Georges Elencwajg 44.8k

4

9

votes

2

answers

167

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The equivalence of two formulae for the Laplace—Beltrami operator

differential-geometry riemannian-geometry

may 3 '11 at 19:52 Glen Wheeler 1,636

1

8

votes

0

answers

204

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Why do universal $\delta$-functors annihilate injectives?

homological-algebra cohomology abelian-categories derived-functors

may 23 '12 at 9:35 Makoto Kato 11.3k

8

votes

2

answers

92

views

A homogeneous set of some kind

logic computability

may 9 '12 at 1:22 Yuval Filmus 25.9k

3

8

votes

1

answer

121

views

Exact sequences with parallel arrows

notation category-theory

dec 13 '11 at 2:37 Zhen Lin 20.9k

2

8

votes

1

answer

262

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Tensor products of infinite-dimensional spaces and other objects

linear-algebra commutative-algebra tensor-products

aug 13 '11 at 13:53 Qiaochu Yuan 117k

1

7

votes

4

answers

442

views

Angle brackets for tuples

soft-question notation math-history

aug 23 at 7:00 Community♦ 1

3

7

votes

1

answer

497

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(Ir)reducibility criteria for homogeneous polynomials

abstract-algebra algebraic-geometry commutative-algebra polynomials

jan 12 '12 at 22:25 Michael Chen 1,864

3

7

votes

3

answers

359

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Homotopy equivalence of two different gluings of $B^n$ and an arbitrary space $X$

homework algebraic-topology

jan 28 '11 at 15:50 Joe Johnson 126 5,482

1

7

votes

1

answer

395

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Measure-preserving transformations and invariant functions

probability-theory measure-theory

dec 29 '10 at 6:00 Matt E 58k

3

6

votes

2

answers

235

views

In what senses are archimedean places infinite?

algebraic-geometry algebraic-number-theory math-history arithmetic-geometry

jan 27 at 3:04 Matt E 58k

4

6

votes

1

answer

76

views

Categories with limits for large diagrams

elementary-set-theory category-theory

sep 26 at 14:30 Zhen Lin 20.9k

1

6

votes

0

answers

150

views

Orientability of the total space of a vector bundle over an oriented manifold

differential-geometry vector-bundles

may 7 '12 at 21:24 Zhen Lin 20.9k

3

6

votes

1

answer

161

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Are these definitions of submanifold equivalent?

differential-geometry definition manifolds

may 7 '12 at 4:11 Daniel Moskovich 1,771

1

6

votes

2

answers

339

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The Dido problem with an arclength constraint

differential-geometry euclidean-geometry plane-curves

feb 21 '11 at 21:12 mhum 519

5

votes

2

answers

722

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Non-existence of a surjection $\aleph_n \to \aleph_{n+1}$, without the axiom of choice

set-theory cardinals axiom-of-choice ordinals

apr 21 at 15:07 Cameron Buie 27.6k

Zhen Lin

75 Questions