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Kritiker der Elche's user avatar
Kritiker der Elche's user avatar
Kritiker der Elche's user avatar
Kritiker der Elche
  • Member for 3 years, 1 month
  • Last seen this week
7 votes
Accepted

Cover definition: When is a set a subset of it's cover's union instead of being equal?

6 votes

When is a quotient map open?

6 votes
Accepted

Can a Torus be a submanifold of a Sphere?

6 votes
Accepted

Do these definitions of limit points agree?

5 votes

Why haven't I heard of the Hausdorff quotient?

5 votes
Accepted

Who is this mathematician on the Fields medal?

5 votes
Accepted

Does there exist a smooth structure on $[0,\infty)$ that induces the standard topology?

4 votes
Accepted

What is my mistake? Degree of a map $S^1 \rightarrow S^1$

4 votes

Proof of "The sum of a convergent and divergent sequence is divergent"

4 votes
Accepted

Urysohn lemma for locally compact spaces

4 votes
Accepted

Does a bijection always generate a natural "induced" topology?

3 votes
Accepted

Is the factor of a topological product closed in the product topology?

3 votes

Is the axiom of choice needed to show that the initial topology is a topology?

3 votes

$R^2-{0}$ is homeomorphic to $R×S^1$

3 votes
Accepted

Fifth Roots of Unity

3 votes

If a topological space $X$ is not path-connected, then the suspension is not simply connected.

3 votes
Accepted

Is $S_{n}(X) \oplus S_{n}(Y) \cong S_{n}(X \amalg Y)$?

3 votes

Proof that if a polynomial is the zero function then all the coefficients are zero.

3 votes

Let $g: \mathbb R \rightarrow \mathbb R$ a differentiable function in $\mathbb R$. $f(x,y) = \frac{g(y)}{1+g^2(x)}$ is differentiable in its domain?

3 votes
Accepted

Equivalence of Frechet derivative to first order expansion

3 votes

Prove that $GL_n(ℝ)$ is a subgroup of $GL_n(ℂ)$.

3 votes
Accepted

Are homotopy equivalences homotopic to each other?

3 votes

Are the Inductive Axiom and the Well ordering Principle really equivalent?

3 votes

Corollary 22.3 in Munkres's book

3 votes
Accepted

Topology of classical compact groups?

3 votes
Accepted

An example of a closed quotient map that is not open

3 votes
Accepted

Error in Spivak's "Calculus on Manifolds". Construction of function composition for proof of change of variables

3 votes
Accepted

Why does this solution to Russell's Paradox not have a contradiction?

3 votes
Accepted

No homotopy with the identity of the unit circle

2 votes
Accepted

Whether covering transformation of universal covering have not fixed point?

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