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John Brevik's user avatar
John Brevik's user avatar
John Brevik's user avatar
John Brevik
  • Member for 9 years, 4 months
  • Last seen more than 1 year ago
25 votes

A standard and rigorous proof using the pigeonhole principle

9 votes

Surfaces in $\mathbb P^3$ not containing any line

6 votes

In a Noetherian integral domain, a principal prime ideal can't have proper non-zero prime ideals

5 votes

Relationship between Eigenvalues

5 votes
Accepted

How is the Set of all Polynomials Equal to the Following Union?

5 votes
Accepted

Morphisms induced by effective divisors on $\mathbf P^1$

4 votes
Accepted

Ideal sheaf of intersection of two surfaces in $\mathbb P^3$

4 votes

Divisor on curve of genus $2$

4 votes
Accepted

Divide a square into different parts

3 votes
Accepted

Resize a rectangle so that one of the dimensions meets its max size and the other side meets the max size or is smaller

3 votes

Suppose that $a$ and $b$ belong to a field of order $8$ and that $a^2 + ab + b^2 =0$ then $a=0$ and $b=0$ .

3 votes

how to prove $R[x]/I [x]=(R/I)[x]$?

3 votes

Proof of Proposition IV 6.1 (Hartshorne page 349)

3 votes
Accepted

Why is a submodule of a free module over a PID is free?

3 votes

Local ring inside a function field of transcendence degree one

3 votes
Accepted

Complete intersection curve

3 votes
Accepted

Prove that $ k[x_1,\ldots,x_4]/ \langle x_1x_2,x_2x_3,x_3x_4,x_4x_1 \rangle$ is not Cohen-Macaulay.

3 votes

Fermat's Last Theorem - Variation with arithmetically descending exponents

3 votes
Accepted

Is a Weil divisor Cartier after some multiple?

3 votes
Accepted

Inseparably ramified primes over $\mathbb{Z}[x]$

3 votes

Prove, that group of order $p^2$ is abelian.

3 votes
Accepted

Is a prime ideal lying between associated primes also an associated prime?

2 votes
Accepted

Is a specific ring extension $B$ of $K[x,y]$ integrally closed? separable?

2 votes
Accepted

Proving that if a function lies within an integral domain, it satisfies the remainder and the root factor theorem

2 votes

If three points on a quadric surface then the line going through them is contained in the quadric

2 votes
Accepted

Affine Cover of $\mathbb{P}^n$

2 votes
Accepted

Correspondence between Weil divisor and Cartier divisor on normal varieties

2 votes

(Family of) plane quartics with two double points

2 votes
Accepted

The exact sequence $0 \rightarrow L(-1) \rightarrow L(0)^2 \rightarrow L(1) \rightarrow 0$

2 votes
Accepted

Space of quintics in $\mathbb{P}^3$ that contain intersection of two quadric surfaces