Zev Chonoles's user avatar
Zev Chonoles's user avatar
Zev Chonoles's user avatar
Zev Chonoles
  • Member for 13 years, 4 months
  • Last seen more than a week ago
81 votes
1 answer
9k views

Thurston's 37th way of thinking about the derivative

51 votes
4 answers
7k views

Is every embedded submanifold globally a level set?

46 votes
5 answers
4k views

Failure of isomorphisms on stalks to arise from an isomorphism of sheaves

35 votes
3 answers
2k views

If every continuous $f:X\to X$ has $\text{Fix}(f)\subseteq X$ closed, must $X$ be Hausdorff?

30 votes
1 answer
2k views

Finite group with isomorphic normal subgroups and non-isomorphic quotients?

28 votes
2 answers
2k views

Meaning of "efface" in "effaceable functor" and "injective effacement"

26 votes
2 answers
1k views

How to prove that $\sum\limits_{n=1}^\infty\frac{(n-1)!}{n\prod\limits_{i=1}^n(a+i)}=\sum\limits_{k=1}^\infty \frac{1}{(a+k)^2}$ for $a>-1$?

23 votes
1 answer
6k views

Why does the definition of an open subscheme / open immersion of schemes allow for an "extra" isomorphism?

18 votes
3 answers
2k views

Examples of rings with ideal lattice isomorphic to $M_3$, $N_5$

18 votes
2 answers
2k views

What is the motivation for defining both homogeneous and inhomogeneous cochains?

17 votes
3 answers
3k views

Discriminant of a monic irreducible integer polynomial vs. discriminant of its splitting field

17 votes
1 answer
2k views

Is there a classification of isolated essential singularities?

16 votes
3 answers
1k views

Topology on the general linear group of a topological vector space

15 votes
1 answer
924 views

How badly can Krull's Hauptidealsatz fail for non-Noetherian rings?

15 votes
1 answer
2k views

Compact submanifolds of $\mathbb{R}^n$ without boundary

15 votes
1 answer
1k views

Finite groups with periodic cohomology

14 votes
1 answer
545 views

Why isn't $H^*(\mathbb{R}P^\infty,\mathbb{F}_2)\cong \mathbb{F}_2[[x]]$?

14 votes
2 answers
2k views

Examples demonstrating that the finitely generated hypothesis in Nakayama's lemma is necessary

14 votes
5 answers
4k views

Correct usage of the phrase "In the sequel"? History? Alternatives?

14 votes
1 answer
538 views

A result of van der Waerden says Galois theory "needs" incomputable sets - what does this mean, exactly?

12 votes
1 answer
2k views

Limit of a decreasing sequence of outer measures is an outer measure?

11 votes
2 answers
1k views

Injection of $E(\mathbb{Q})_{\text{tors}}$ into $\tilde{E}(\mathbb{F}_p)$?

10 votes
1 answer
591 views

Isomorphism between $I_G/I_G^2$ and $G/G'$

9 votes
1 answer
405 views

How often does the Jacobi symbol incorrectly identify quadratic residues?

9 votes
2 answers
215 views

Demonstrating the value of abstracting away from elements/subsets to maps

9 votes
3 answers
990 views

Without choosing bases, how to show that the determinant is multiplicative in this sense?

9 votes
2 answers
1k views

Justification for this manipulation in a proof of the first variation of energy formula

8 votes
1 answer
706 views

Do the notions of weak and weak* convergence coincide for $\ell^1(\mathbb{N})$?

8 votes
1 answer
1k views

Roots of unity and field extensions

7 votes
4 answers
3k views

Drawing a thickened Möbius strip in Mathematica