Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard
  • Member for 14 years, 5 months
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98 votes
16 answers
28k views

What if Current Foundations of Mathematics are Inconsistent? [closed]

86 votes
1 answer
5k views

Are there non-scalar endomorphisms of the functor $V\mapsto V^{**}/V$?

44 votes
17 answers
16k views

What is your favorite proof of Tychonoff's Theorem?

26 votes
2 answers
2k views

Is every commutative ring a limit of noetherian rings?

20 votes
1 answer
951 views

Example of an additive functor admitting no right derived functor

19 votes
2 answers
744 views

Is $K[[x_1,x_2,\dots]]$ an $\mathfrak m$-adically complete ring?

19 votes
2 answers
1k views

If $\mathcal C^{\mathcal C}$ is equivalent to $\mathcal C$, is $\mathcal C$ necessarily equivalent to a category with one object and one morphism?

14 votes
2 answers
663 views

$\mathcal A^{\mathcal A}\sim\mathcal B^{\mathcal B}\implies\mathcal A\sim\mathcal B\ ?$ (Does A^A ~ B^B imply A ~ B? --- A, B categories)

13 votes
0 answers
291 views

Is $\mathrm{Hom}(P^i,P^j)$ a finite set? ($P=$ power set functor, $i\equiv j\bmod2$)

12 votes
1 answer
448 views

Does the Cantor-Schröder-Bernstein Theorem hold in the category opposite to the category of noetherian commutative rings?

11 votes
0 answers
272 views

Does every finite poset have a rigid endomorphism?

10 votes
1 answer
402 views

Does every set have a rigid self-map?

10 votes
1 answer
253 views

Is $\operatorname{Hom}(F,G)$ finite if $F$ and $G$ are endofunctors of the category of finite sets?

10 votes
2 answers
609 views

Equivalence of the definitions of a sheaf in SGA4 and in "Categories and Sheaves"

10 votes
1 answer
353 views

Is the product of Jacobson rings a Jacobson ring?

9 votes
1 answer
800 views

Are epimorphic endomorphisms of noetherian commutative rings always injective?

8 votes
1 answer
3k views

dim Hom(V,W) =?

8 votes
4 answers
2k views

Are there locally compact groups which have no compact open subgroups and no discrete infinite cyclic subgroups?

7 votes
1 answer
529 views

Prescribing the dimension of intersections of sub-vector spaces

6 votes
0 answers
189 views

Isomorphism of hyperreal fields viewed as extensions of the field of reals

5 votes
1 answer
175 views

Comparing $\mathcal C$ and $\mathcal C^{\mathcal C}$ (where $\mathcal C$ is a category)

5 votes
0 answers
101 views

Is there a positive integer k such that any endomorphism of any free module over any commutative ring is a linear combination of k idempotents?

4 votes
1 answer
542 views

Generators of a certain ideal

4 votes
0 answers
474 views

Endomorphisms of free modules and extension of scalars

2 votes
1 answer
240 views

Are unique prime ideal factorization domains locally noetherian?

2 votes
0 answers
98 views

Existence of a certain derived functor

1 vote
0 answers
123 views

Preservation of direct sums and finite generation

1 vote
0 answers
152 views

Possible similarities between a category and its category of endofunctors