User Simon Henry

18 votes

Why the sphere spectrum is more correct than $\mathbb{Z}$?

answered Nov 4, 2022 at 13:55

18 votes

Accepted

Non-commutative duality I: Which C*-algebras are (isomorphic to a) convolution algebra?

answered Oct 3, 2020 at 13:13

18 votes

Accepted

Toposes with only preorders of points

answered Oct 5, 2020 at 13:16

18 votes

Is Bauer–Hanson’s result “there is a topos where the Dedekind reals are countable” novel?

answered Aug 23, 2023 at 16:11

17 votes

Accepted

Does every category with a subobject classifier embed into a topos?

answered Sep 17, 2020 at 21:19

17 votes

Accepted

Is AC equivalent over ZF to 'every fibration can be equipped with a cleavage'?

answered Jan 20, 2021 at 3:31

17 votes

Accepted

What is the category of covariant and contravariant functors?

answered Apr 1, 2021 at 23:55

17 votes

Are there categories whose internal hom is somewhat 'exotic'?

answered Aug 18, 2019 at 18:38

17 votes

Accepted

Topos with enough points but not coherent

answered Mar 9, 2022 at 18:11

17 votes

What is the geometric significance of fibered category theory in topos theory?

answered Sep 30, 2018 at 20:38

16 votes

What does an etale topos classify?

answered Jul 8, 2013 at 6:25

16 votes

How to express in categorical language that in some toposes not all complex numbers have square roots

answered Oct 26, 2021 at 15:19

16 votes

Why is $1$ not a dense sub-site in a group with the trivial Grothendieck topology?

answered Aug 19, 2022 at 15:43

16 votes

Accepted

Are equivalences of categories stable under filtered colimits?

answered Jan 4, 2021 at 15:06

16 votes

Accepted

How can we make precise the notion that a finite-dimensional vector space is not canonically isomorphic to its dual via category theory?

answered Mar 9, 2021 at 19:30

15 votes

Accepted

What is the smallest variety of algebras containing all fields?

answered Mar 22, 2012 at 9:24

14 votes

Accepted

Between compact and locally uniform: What is the name of this convergence?

answered Nov 18, 2014 at 14:37

14 votes

Accepted

Truncation of infinity-categories

answered Sep 19, 2020 at 20:53

14 votes

Accepted

A multicategory is a ... with one object?

answered Jan 11, 2019 at 13:47

14 votes

Accepted

Higher $\infty$-categories

answered Mar 2, 2019 at 11:25

14 votes

Why is Kan's $Ex^\infty$ functor useful?

answered Mar 6, 2019 at 8:37

14 votes

Localic or topos-theoretic definition of $\operatorname{Spec}$

answered Jan 25, 2023 at 15:30

13 votes

Accepted

Tensor product of sites

answered May 25, 2023 at 16:02

13 votes

Accepted

$(n,1)$-dagger categories

answered Jul 26, 2022 at 10:11

13 votes

sSet-enriched categories, quasi-categories and the model-independent theory

answered Sep 24, 2022 at 2:32

13 votes

Accepted

What are projective locales / injective frames?

answered Jun 29, 2021 at 19:56

13 votes

Accepted

Equivalences of categories of sheaves vs categories of $\infty$-Stack

answered Dec 6, 2018 at 23:31

13 votes

Correspondence between classes of model categories and classes of $\infty$-categories

answered Oct 1, 2019 at 15:44

13 votes

Accepted

Characterization of Stone-Cech compactifications

answered Sep 23, 2012 at 7:54

13 votes

Accepted

Why are finite cell complexes also finite as infinity-categories?

answered Nov 6, 2018 at 14:42

Stack Exchange Network

308 Answers

Why the sphere spectrum is more correct than $\mathbb{Z}$?

Non-commutative duality I: Which C*-algebras are (isomorphic to a) convolution algebra?

Toposes with only preorders of points

Is Bauer–Hanson’s result “there is a topos where the Dedekind reals are countable” novel?

Does every category with a subobject classifier embed into a topos?

Is AC equivalent over ZF to 'every fibration can be equipped with a cleavage'?

What is the category of covariant and contravariant functors?

Are there categories whose internal hom is somewhat 'exotic'?

Topos with enough points but not coherent

What is the geometric significance of fibered category theory in topos theory?

What does an etale topos classify?

How to express in categorical language that in some toposes not all complex numbers have square roots

Why is $1$ not a dense sub-site in a group with the trivial Grothendieck topology?

Are equivalences of categories stable under filtered colimits?

How can we make precise the notion that a finite-dimensional vector space is not canonically isomorphic to its dual via category theory?

What is the smallest variety of algebras containing all fields?

Between compact and locally uniform: What is the name of this convergence?

Truncation of infinity-categories

A multicategory is a ... with one object?

Higher $\infty$-categories

Why is Kan's $Ex^\infty$ functor useful?

Localic or topos-theoretic definition of $\operatorname{Spec}$

Tensor product of sites

$(n,1)$-dagger categories

sSet-enriched categories, quasi-categories and the model-independent theory

What are projective locales / injective frames?

Equivalences of categories of sheaves vs categories of $\infty$-Stack

Correspondence between classes of model categories and classes of $\infty$-categories

Characterization of Stone-Cech compactifications

Why are finite cell complexes also finite as infinity-categories?