Skip to main content
johnnycrab's user avatar
johnnycrab's user avatar
johnnycrab's user avatar
johnnycrab
  • Member for 9 years, 11 months
  • Last seen more than a month ago
6 votes
1 answer
520 views

Cancellation in quotient of fractional ideals

6 votes
1 answer
308 views

Non-zero-divisor in quotient ring: Not a unit over minimal prime?

5 votes
1 answer
780 views

Proving 20-th cyclotomic field has class number one.

4 votes
1 answer
624 views

Kapranov's Theorem for tropical hypersurfaces: Understanding closure

4 votes
3 answers
3k views

$p$ prime, $G$ group of order $2p$, normal subgroup $N$ of order $2$. Show that $G$ is Abelian.

4 votes
0 answers
121 views

Sheafification of presheaf with support is equal to sheafification with support?

2 votes
3 answers
287 views

Find function $f: U \subset \mathbb{R}^2 \to \mathbb{R}$ with $||Df(x,y)|| \leq 1$ such that $P,Q \in U$ exist with $|f(P) - f(Q)| > || P-Q||$

2 votes
1 answer
80 views

Let $f$ be a polynomial with $\deg f = 2n + 1$, and $a_1, .\dots, a_{2n+1}$ that $f(a_i) \in \{+1, -1\}$. Show $f$ is irreducible

1 vote
0 answers
95 views

Where's my error? Probability three of a kind, three dice rolled once [duplicate]

1 vote
0 answers
630 views

Proving "up to unique isomorphism": Universal property of cokernel

1 vote
0 answers
222 views

$R$ integral domain, $P$ projective and injective module $\implies P=0$ or $R$ is field of fractions [duplicate]

1 vote
1 answer
35 views

Is there an endomorphism $F$ and a vector $v$, such that $F$-invariant $span\{v, F(v), F^2(v), ...\}$ is decomposable

1 vote
1 answer
360 views

Irreducible Laurent polynomial in multiple variables: Ideal intersection

1 vote
1 answer
150 views

Example of Banach ring with non-closed ideal

1 vote
1 answer
565 views

Very affine varieties form basis of Zariski Topology

1 vote
0 answers
17 views

Soft sheaves on $T_1$-space

1 vote
1 answer
195 views

Closed subscheme intersected with open affine: Irreducible?

1 vote
1 answer
248 views

Generic point of closed subscheme meeting multiple irreducible components.

1 vote
1 answer
214 views

Inductive order of vanishing along subvarieties.

1 vote
0 answers
131 views

Čech cohomology of fine sheaves

0 votes
0 answers
272 views

Closed subscheme of smooth scheme

0 votes
1 answer
453 views

Integrally closed domain preserved under prime quotient. Where is my mistake?

0 votes
2 answers
745 views

Understanding proof for $\sum_{k=1}^{n-1}{\sin{\frac{2\pi k}{n}}} = 0$

0 votes
1 answer
172 views

Connecting class group theory and towers of Galois extensions

0 votes
1 answer
530 views

Discriminant of $\mathbb{Z}$-submodule in number field $K$.