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Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard
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32 Answers

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56 votes

Quick proofs of hard theorems

21 votes

Dimension of infinite product of vector spaces

18 votes

Errata for Atiyah–Macdonald

18 votes

Examples of common false beliefs in mathematics

17 votes

Cardinality of the permutations of an infinite set

17 votes
Accepted

"Sums-compact" objects = f.g. objects in categories of modules?

10 votes

Galois theory timeline

9 votes

Applications of the Chinese remainder theorem

7 votes

Suggestions for good books on class field theory

7 votes
Accepted

When matrices commute

7 votes
Accepted

Closedness of finite-dimensional subspaces

6 votes

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

6 votes

Examples of common false beliefs in mathematics

5 votes

Expressing $-\operatorname{adj}(A)$ as a polynomial in $A$?

5 votes
Accepted

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

5 votes

Posets isomorphic to their endomorphism poset

5 votes

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

4 votes

Is PA consistent? do we know it?

4 votes

Why are (pre)sheaves defined as contravariant functors? Why not just reverse the arrows in the first place?

4 votes

Can a vector space over an infinite field be a finite union of proper subspaces?

4 votes

Examples of common false beliefs in mathematics

3 votes

Subset of the plane that intersects every line exactly twice

3 votes

Math paper authors' order

3 votes

Localizing an arbitrary additive category

2 votes

Taylor's theorem and the symmetric group

2 votes

What are all the natural maps between iterated duals of vector spaces, and equations between these?

2 votes

What does it mean for a mathematical statement to be true?

2 votes

Shortest/Most elegant proof for $L(1,\chi)\neq 0$

1 vote

How would one even begin to try to prove that a simple number-theoretic statement is undecidable?

1 vote

Unbounded operator bounded in a dense subset

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