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57Jimmy
  • Member for 5 years, 9 months
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20 votes

Why is the Operator Norm so hard to calculate?

8 votes

Do Monoid Homomorphisms preserve the identity?

7 votes

Why is $\sum \frac{1}{\ln(n)^{\ln n}}$ convergent?

7 votes
Accepted

What is the difference between lemma, axiom, definition, corollary, etc?

6 votes

Existence of a maximal set (with respect to set inclusion) having a certain property

6 votes
Accepted

Jacobson radical = nilradical iff every open set of $\text{Spec}A$ contains a closed point.

5 votes

When people say "an algebra" do they always mean "an algebra over a field"?

5 votes

Number of solutions of equation $ a ^ x = 2016x$

5 votes

What's the precise meaning of the expression "induced by" in mathematics?

5 votes
Accepted

Prove symmetries of eigenvalues of symplectic matrices

5 votes
Accepted

Different definitions of closed differential form

5 votes

How is a prime a product of primes? [singleton products]

5 votes
Accepted

Why isn't every vector bundle morphism an isomorphism?

4 votes

How does one take the derivative of $\ln|\ln|x||$?

4 votes
Accepted

differentiate cos x inside integration

4 votes
Accepted

Operations that are commutative but non-associative on a set of only two elements?

4 votes
Accepted

How to show diffeomorphisms map boundaries to boundaries?

4 votes
Accepted

$H, K$ conjugate subgroups of $G$, then $G/H$ and $G/K$ are isomorphic as G-sets

4 votes
Accepted

Bounded function and second derivative implies bounded derivative.

4 votes
Accepted

Show that R[x]/(x^7 +1) is not an integral domain.

4 votes
Accepted

Show that any integer can be expressed as $S^{k}_{n}$

4 votes

the number of maximal ideal in $Zp^4$

4 votes
Accepted

Counter-example: If $J$ is prime then $f^{-1} (J) $ is prime. $f$ need not be unital.

3 votes
Accepted

Definition of product implies the existence of continuous function?

3 votes
Accepted

Prove/Disprove: Sum of im/ker of linear transformation contained in ker/im of each linear trasnfromation

3 votes
Accepted

Can find common principal open subsets in the intersection of two open affine subschemes

3 votes
Accepted

Values for which the linear map is injective

3 votes

Why does factoring out $\pm$ from an expression introduce a minus sign?

3 votes
Accepted

Orthogonal linear transformation.

3 votes
Accepted

Proving (2,5) is an open set?

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