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Randall's user avatar
Randall's user avatar
Randall's user avatar
Randall
  • Member for 6 years, 10 months
  • Last seen this week
75 votes

"Naturally occurring" non-Hausdorff spaces?

29 votes
Accepted

Do cubics always have one real root?

29 votes
Accepted

What's a "deleted neighborhood"? (other than very very confusing)

27 votes

Why must be the additive and multiplicative identities in a field be different?

21 votes
Accepted

Is $\Bbb R/\Bbb Z$ isomorphic to $\Bbb R/2\Bbb Z$?

19 votes

What's the difference between biconditional iff and logical equivalence?

14 votes

Is there a metric on the reals $\Bbb R$ so that a subset of $\Bbb R$ is open iff its complement is finite?

14 votes

For vector spaces $V,W$ over $\mathbf{k}$, is every additive $\phi: V \to W$ also $\mathbf{k}$-linear?

13 votes

Is $G/H\times H\simeq G$ topologically?

13 votes

What does it mean when I say that addition/multiplication for an equivalence relation is well defined?

13 votes

Argument for infinite intersection of compacts is compact

12 votes
Accepted

What does the notation $q^k || n$ mean?

12 votes
Accepted

Problem with the definition of a discrete topology

11 votes

Is indefinite integration suspect?

11 votes
Accepted

If an operation can be represented with other associative operations can we assume it is associative?

10 votes

Why is the continuity of the binary operation required in the definition of a topological group?

10 votes

How strong is homotopy equivalence?

9 votes

Why the square root of any decimal number between 0 and 1 always come out to be greater than the number itself?

9 votes
Accepted

How to prove that: $\int_{-1}^{1} \frac{1}{x^2-1}dx$ diverges?

8 votes

What is the smallest order of a group to have non abelian proper subgroup?

8 votes
Accepted

Is a fibre bundle with contractible fibre a homotopy equivalence?

8 votes
Accepted

$\mathbb{R}\cong X\times Y$ (homeomorphic) implies $X$ or $Y$ is a point.

8 votes

"Naturally occurring" non-Hausdorff spaces?

8 votes
Accepted

Why can't we prove that union of infinite no of countable sets is also countable by induction?

8 votes

if $f$ is continuous on $(a,b)$, then $f$ has a maximum - Proof refutation

8 votes
Accepted

Can there be more than one global maximums of a function?

8 votes
Accepted

I guess $G/N\cong G'/N'$ doesn't hold in this case, but I cannot prove that.

7 votes
Accepted

$10$ people ($6$ male, $4$ female) divided into $2$ equal groups: what is the probability that all females are in the same group?

7 votes

What's actually the definition of the product of morphisms?

7 votes
Accepted

Does there exist a space which has trivial fundamental group but is not path connected?

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