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Simon Henry's user avatar
Simon Henry's user avatar
Simon Henry
  • Member for 12 years, 9 months
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307 Answers

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73 votes
Accepted

Why did Voevodsky consider categories "posets in the next dimension", and groupoids the correct generalisation of sets?

55 votes
Accepted

Constructive algebraic geometry

47 votes

What is the mistake in the proof of the Homotopy hypothesis by Kapranov and Voevodsky?

38 votes
Accepted

Could groups be used instead of sets as a foundation of mathematics?

36 votes
Accepted

Current status of Grothendieck's homotopy hypothesis and Whitehead's algebraic homotopy programme

29 votes

Why is the bicategory viewpoint useful?

28 votes
Accepted

Finding a closed form for $\sum_{k=1}^{\infty}\frac{1}{(2k)^5-(2k)^3}$

27 votes

Does Zorn's Lemma imply a physical prediction?

27 votes

How many morphisms from 1 to 1+1 can there be?

26 votes
Accepted

Why do we care about small sets?

26 votes
Accepted

The formal p-adic numbers

23 votes
Accepted

Locales as geometric objects

23 votes

What is the intuition for higher homotopy groups not vanishing?

22 votes
Accepted

Why is the theory of small categories not algebraic?

22 votes
Accepted

Is there a higher analog of "category with all same side inverses is a groupoid"?

22 votes
Accepted

Why are operads sometimes better than algebraic theories?

22 votes
Accepted

Useful ideas in category theory which violate the principle of equivalence

21 votes
Accepted

Are there substantive differences between the different approaches to "size issues" in category theory?

21 votes
Accepted

There are no abstract categories

21 votes
Accepted

$\operatorname{Ind}(C^I) = \operatorname{Ind}(C)^I$?

21 votes

A sheaf is a presheaf that preserves small limits

21 votes
Accepted

Complete Boolean algebra not isomorphic to a $\sigma$-algebra

20 votes
Accepted

Is there a universal property characterizing the category of compact Hausdorff spaces?

20 votes
Accepted

What is a module over a Boolean ring?

20 votes
Accepted

Why do elementary topoi have pullbacks?

19 votes
Accepted

An extension of the Galois theory of Grothendieck

19 votes
Accepted

Is each closed convex set a manifold with corners?

19 votes

Are dagger categories truly evil?

19 votes
Accepted

"Spatial (geometrical)" realization of Elementary topos?

18 votes

Why do we need model categories?

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