johnnycrab
  • Member for 7 years, 5 months
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1 answers
6 votes
196 views
1 bookmarks
Non-zero-divisor in quotient ring: Not a unit over minimal prime?
1 answers
5 votes
362 views
1 bookmarks
Cancellation in quotient of fractional ideals
1 answers
5 votes
594 views
2 bookmarks
Proving 20-th cyclotomic field has class number one.
0 answers
4 votes
68 views
2 bookmarks
Sheafification of presheaf with support is equal to sheafification with support?
1 answers
4 votes
410 views
2 bookmarks
Kapranov's Theorem for tropical hypersurfaces: Understanding closure
3 answers
4 votes
2k views
$p$ prime, $G$ group of order $2p$, normal subgroup $N$ of order $2$. Show that $G$ is Abelian.
1 answers
2 votes
65 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
3 answers
2 votes
162 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 $|f(P) - f(Q)| > || P-Q||$
1 answers
1 votes
323 views
Very affine varieties form basis of Zariski Topology
0 answers
1 votes
60 views
Čech cohomology of fine sheaves
1 answers
1 votes
122 views
Inductive order of vanishing along subvarieties.
1 answers
1 votes
152 views
Generic point of closed subscheme meeting multiple irreducible components.
1 answers
1 votes
128 views
Closed subscheme intersected with open affine: Irreducible?
0 answers
1 votes
16 views
Soft sheaves on $T_1$-space
1 answers
1 votes
110 views
Example of Banach ring with non-closed ideal
1 answers
1 votes
262 views
Irreducible Laurent polynomial in multiple variables: Ideal intersection
0 answers
1 votes
153 views
2 bookmarks
$R$ integral domain, $P$ projective and injective module $\implies P=0$ or $R$ is field of fractions
0 answers
1 votes
532 views
Proving "up to unique isomorphism": Universal property of cokernel
0 answers
1 votes
92 views
1 bookmarks
Where's my error? Probability three of a kind, three dice rolled once
1 answers
1 votes
33 views
Is there an endomorphism $F$ and a vector $v$, such that $F$-invariant $span\{v, F(v), F^2(v), ...\}$ is decomposable
1 answers
0 votes
190 views
Integrally closed domain preserved under prime quotient. Where is my mistake?
0 answers
0 votes
128 views
Closed subscheme of smooth scheme
1 answers
0 votes
142 views
Connecting class group theory and towers of Galois extensions
1 answers
0 votes
385 views
1 bookmarks
Discriminant of $\mathbb{Z}$-submodule in number field $K$.
2 answers
0 votes
220 views
Understanding proof for $\sum_{k=1}^{n-1}{\sin{\frac{2\pi k}{n}}} = 0$