JSchlather's user avatar
JSchlather's user avatar
JSchlather's user avatar
JSchlather
  • Member for 13 years, 5 months
  • Last seen more than 1 year ago
106 votes

Can you answer my son's fourth-grade homework question: Which numbers are prime, have digits adding to ten and have a three in the tens place?

77 votes
Accepted

Paul Erdos's Two-Line Functional Analysis Proof

30 votes
Accepted

Compute $\operatorname{Hom}_{\mathbb{Z}} ( \mathbb{Q}, \mathbb{Z})$

20 votes

Normal subgroup of prime index

17 votes
Accepted

Extensions of degree two are Galois Extensions.

16 votes

Show that for a finite metric space A, every subset is open

16 votes

Non-associative, non-commutative binary operation with a identity

15 votes

Good Book On Combinatorics

15 votes
Accepted

How to prove that $\mathbb{Q} \subset \mathbb{R}$ is not locally compact directly?

15 votes

Why is the supremum of the empty set $-\infty$ and the infimum $\infty$?

14 votes

What is the current status of Vinay Deolalikar's proof that P is not equal to NP

13 votes
Accepted

Finite sub cover for $(0,1)$

13 votes
Accepted

Can we always find a primitive element that is a square?

13 votes
Accepted

Irreducibility of $X^n - 2$ over $\mathbf Z[i]$.

13 votes

How to show that a finite commutative ring without zero divisors is a field?

12 votes
Accepted

What would happen if we created a vector space over an integral domain/ring.

12 votes
Accepted

$[L:K]=n!\ \Longrightarrow \ f$ is irreducible and $\text{Gal}(L/K)\cong S_n.$

11 votes
Accepted

Involutions and Abelian Groups, II.

11 votes
Accepted

Cauchy's Residue Theorem on a Singularity Outside a Contour

10 votes
Accepted

From Counterexamples in Topology, question on the lower limit topology

10 votes
Accepted

Is there any number greater than 8 of the form $2^{2k+1}$ which is the sum of a prime and a safe prime?

10 votes
Accepted

Showing that that the torus is not a retract of a $3$-sphere

10 votes

Minimal polynomial, determinants and invertibility

10 votes
Accepted

Are functions that map dense sets to dense sets continuous?

9 votes
Accepted

Subfields of Rings

9 votes
Accepted

What algebraic structure is the set of natural numbers and addition?

9 votes
Accepted

Computing the minimal polynomial over $\mathbb{Q}(\sqrt{3})$

9 votes
Accepted

In a metric space, if a set is compact, then it is closed: improving proof

9 votes
Accepted

Schwarz's Lemma, fixed points question

9 votes
Accepted

Unconventional Galois theory in Qual

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