Mark's user avatar
Mark's user avatar
Mark's user avatar
Mark
  • Member for 8 years, 5 months
  • Last seen more than a month ago
7 votes
Accepted

Is a surjection from the natural numbers enough to show that a set is countable?

6 votes
Accepted

Discriminant of the depressed cubic

5 votes

Degree of $\mathbb{Q}(\xi_{p^{2}})$ over $\mathbb{Q}$.

5 votes

Show that the field of fractions of $\mathbb{Z}[[x]]$ is properly contained in $\Bbb Q((x))$

5 votes
Accepted

Given real angles $\phi_1,\ldots,\phi_N$, there exist infinitely many integers $n$ such that $\cos(n\phi_k) > 0$ for all $k$.

4 votes

unique factorization in polynomial modulo $p^k$

3 votes
Accepted

Check whether field extension is splitting field

3 votes
Accepted

A interesting question on Skew-symmetric matrix...finding the determinant.

3 votes
Accepted

Advice on mathematical thinking and problem-solving

3 votes

For $a^3+b^3+c^3=3$ prove that $a^4b+b^4c+c^4a\leq3$

3 votes

Why can $2^3$ be defined but $0^0$ cannot

3 votes

Well defined function meaning

3 votes

How to prove Euler's formula: $e^{i\varphi}=\cos(\varphi) +i\sin(\varphi)$?

2 votes

Why can't we define more elementary functions?

2 votes
Accepted

How to "embed" ${2^{\bf N}}$ into ${{\bf R}}$?

2 votes
Accepted

Is $\mathbb{F}$ an algebraic extension of $k$ if $\dim_k V < |k|$?

2 votes
Accepted

Show that for any $k$-cycle $(a_1 a_2...a_k) \in S_n$, and for any permutation $\pi \in S_n$, $\pi(a_1...a_k)\pi^{-1}=(\pi(a_1)..\pi(a_k))$

2 votes

Prove that $\sin\frac{\pi}{7}\sin\frac{2\pi}{7}\sin\frac{3\pi}{7}=\frac{\sqrt{7}}{8}$.

2 votes
Accepted

Sylow system of a group

2 votes

Primes $p=1\pmod 5$

2 votes

Why is the genus of $y^2 = x^4 + 1$ not $3$ but $1$?

2 votes

Find the minimal $a+b$.

2 votes

Is $\prod_{1\leq i< j\leq n} \frac{a_i - a_j}{i-j}$, with distinct integers $a_i$, an integer?

1 vote

Number of terms in factors of polynomial

1 vote

Is the square root of a 2 by 2 matrix unique?

1 vote

Proving a combinatoric identity

1 vote

Understanding the homomorphism: $(A, +) \cong \mathbb{Z} / p^2 \mathbb{Z}$

1 vote
Accepted

Irreducibility over $\mathbb{F}_5$

1 vote

Suppose that both $a$ and $a^2$ are roots of an irreducible polynomial $f$ over $\mathbb{Q}$. Show that $a^4,a^8....$ are also roots of f

1 vote
Accepted

Galois Correspondence