User Zhen Lin

69 votes

Accepted

Why did my friend lose all his money?

answered Aug 28, 2012 at 9:05

53 votes

Why is the category of fields seemingly so poorly behaved?

abstract-algebra category-theory field-theory

answered Jul 14, 2020 at 2:10

50 votes

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Understanding Ramification Points

riemann-surfaces

answered May 29, 2012 at 10:59

47 votes

Zero probability and impossibility

probability-theory

answered May 24, 2011 at 19:58

47 votes

In set theory, how are real numbers represented as sets?

elementary-set-theory

answered Sep 8, 2011 at 15:45

45 votes

What are differences between affine space and vector space?

linear-algebra affine-geometry

answered Aug 1, 2014 at 14:35

43 votes

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Do De Morgan's laws hold in propositional intuitionistic logic?

logic propositional-calculus constructive-mathematics

answered Mar 14, 2012 at 19:41

42 votes

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Is Zorn's lemma required to prove the existence of a maximal atlas on a manifold?

manifolds axiom-of-choice

answered Sep 22, 2011 at 6:35

42 votes

What is the 'implicit function theorem'?

real-analysis intuition multivariable-calculus

answered Mar 10, 2011 at 18:49

41 votes

What are the Axiom of Choice and Axiom of Determinacy?

set-theory intuition axiom-of-choice

answered Jul 20, 2011 at 10:55

40 votes

When to learn category theory?

abstract-algebra category-theory education learning

answered Feb 9, 2011 at 7:41

40 votes

Accepted

Quotient objects, their universal property and the isomorphism theorems

abstract-algebra category-theory

answered Sep 1, 2011 at 15:50

37 votes

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Why must we distinguish between rational and irrational numbers?

irrational-numbers rational-numbers

answered Dec 9, 2012 at 20:27

36 votes

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Why use ZF over NFU?

set-theory alternative-set-theories

answered Sep 9, 2012 at 18:30

34 votes

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Are some real numbers "uncomputable"?

algorithms computability

answered Aug 17, 2011 at 12:47

34 votes

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Surjectivity implies injectivity and conversely

functions elementary-set-theory

answered Sep 9, 2011 at 10:37

29 votes

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Tautological 1-form on the cotangent bundle

differential-geometry symplectic-geometry

answered Dec 6, 2012 at 9:25

29 votes

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Does taking the direct limit of chain complexes commute with taking homology?

category-theory homological-algebra homology-cohomology

answered May 24, 2013 at 17:31

28 votes

Best way to learn Algebraic Geometry?

reference-request algebraic-geometry soft-question learning

answered Dec 26, 2011 at 8:09

28 votes

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Question about perfect pairings

abstract-algebra tensor-products

answered Feb 12, 2012 at 12:50

26 votes

Accepted

Good references for stacks

reference-request algebraic-geometry soft-question

answered Dec 10, 2012 at 0:16

26 votes

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Does "cheap nonstandard analysis" take place in a topos?

category-theory nonstandard-analysis topos-theory

answered Jul 29, 2013 at 9:09

23 votes

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Questions regarding Riemann's rearrangement theorem

sequences-and-series

answered May 23, 2011 at 17:20

22 votes

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Vector bundle transitions and Čech cohomology

differential-geometry vector-bundles

answered Sep 17, 2012 at 12:35

21 votes

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Gluing sheaves - can we realize $\mathcal{F}(W)$ as some kind of limit?

algebraic-geometry category-theory sheaf-theory

answered Jul 30, 2013 at 18:15

20 votes

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What is a Lawvere-Tierney topology?

category-theory topos-theory

answered Aug 2, 2012 at 5:39

20 votes

Why is Peano arithmetic undecidable?

number-theory logic peano-axioms

answered Jan 7, 2011 at 17:07

19 votes

Accepted

Confusion about Homotopy Type Theory terminology

type-theory homotopy-type-theory

answered Aug 3, 2013 at 20:08

18 votes

How to prove the mathematical induction is true?

proof-theory

answered Feb 27, 2011 at 10:56

18 votes

Accepted

Is an equivalence an adjunction?

category-theory adjoint-functors

answered Dec 6, 2013 at 13:09

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1,130 Answers

Why did my friend lose all his money?

Why is the category of fields seemingly so poorly behaved?

Understanding Ramification Points

Zero probability and impossibility

In set theory, how are real numbers represented as sets?

What are differences between affine space and vector space?

Do De Morgan's laws hold in propositional intuitionistic logic?

Is Zorn's lemma required to prove the existence of a maximal atlas on a manifold?

What is the 'implicit function theorem'?

What are the Axiom of Choice and Axiom of Determinacy?

When to learn category theory?

Quotient objects, their universal property and the isomorphism theorems

Why must we distinguish between rational and irrational numbers?

Why use ZF over NFU?

Are some real numbers "uncomputable"?

Surjectivity implies injectivity and conversely

Tautological 1-form on the cotangent bundle

Does taking the direct limit of chain complexes commute with taking homology?

Best way to learn Algebraic Geometry?

Question about perfect pairings

Good references for stacks

Does "cheap nonstandard analysis" take place in a topos?

Questions regarding Riemann's rearrangement theorem

Vector bundle transitions and Čech cohomology

Gluing sheaves - can we realize $\mathcal{F}(W)$ as some kind of limit?

What is a Lawvere-Tierney topology?

Why is Peano arithmetic undecidable?

Confusion about Homotopy Type Theory terminology

How to prove the mathematical induction is true?

Is an equivalence an adjunction?