Damian Reding's user avatar
Damian Reding's user avatar
Damian Reding's user avatar
Damian Reding
  • Member for 9 years, 4 months
  • Last seen this week
  • Rotterdam, Netherlands
48 votes

What are some things we can prove they must exist, but have no idea what they are?

20 votes

Deep theorem with trivial proof

11 votes

$f$ is discontinuous $\iff$ kernel($f$) is dense in X

9 votes
Accepted

If we have two functions that have composition differentiable does it mean both are differentiable?

7 votes
Accepted

Why does a piecewise constant function not have a primitive function?

7 votes

Is there a branch of Mathematics which connects Calculus and Discrete Math / Number Theory?

7 votes

Wanted: A simple and didactically optimized integration theory

6 votes
Accepted

How to show that the limit exists?

6 votes

Why the existence of Taylor series doesn't imply it coverges to the original function

6 votes

If $B^2$= this matrix, find $B$

5 votes

"Magical" identity between primitives.

5 votes

If $\partial X\subset Y$, then $X\cup Y$ is connnected.

4 votes

If S is a bounded set, then inf(S) and sup(s) belong to the closure of S

4 votes

From a bag containing $10$ pairs of socks, how many must a person pull out to ensure that they get at least $2$ matching pairs of socks?

4 votes

Why does $\cos(x) + \cos(y) - \cos(x + y) = 0$ look like an ellipse?

4 votes
Accepted

how to prove if $\det A=\det B$ then $A=CB$?

4 votes

Uniform convergence of sequence of function necessary for switching limits

4 votes

How to define trigonometric functions analytically and elementary

4 votes
Accepted

Let $f(x,y)$ be polynomial, and $W = \left\{ {(x,y) \in R,f(x,y) = 0} \right\}$. Why does $W^o = \emptyset$??

3 votes
Accepted

Is this graph planar?

3 votes

Prove that the set of integers of the form $2^k−3$ contains an infinite subset of relatively prime numbers

3 votes

For all positive real numbers $x$, if $x$ is irrational, at least one of the numbers $x+\sqrt{2} $ and $x^2 - 2$ is irrational.

3 votes

Algebra - Prove this is a Ring

3 votes

Let $A\in M_n$, and $A=0$. What is $\dim(\ker(A))=$?

3 votes

Derivates of function and limits

3 votes
Accepted

Existence of an metric or a topology so that every subset is compact

3 votes

Show that $\mathbb{Q}(\sqrt{5}+\sqrt[3]{2})=\mathbb{Q}(\sqrt{5},\sqrt[3]{2})$.

3 votes

Is a separable and metrizable space second countable?

2 votes

Can someone show by vector means that any inscribed angle in a semicircle is a right angle

2 votes

Why does f'(0) not exist for this piecewise defined function?