user avatar
user avatar
user avatar
Mirko
  • Member for 7 years, 8 months
  • Last seen more than a month ago
13 votes
1 answer
434 views

Order-preserving map of regressive functions on $\omega_1$

10 votes
2 answers
256 views

Partitioning the plane into three sets each intersecting the vertices of every square with side 1?

10 votes
0 answers
143 views

Building "oppositely bitten rectangles" with consecutive squares

6 votes
1 answer
131 views

Define $A^{-1}$ (in some cases) even if $A$ is not an invertible matrix

5 votes
1 answer
216 views

Is there a $k$ such that $2^n$ has $6$ as one of its digits for all $n\ge k$?

4 votes
3 answers
177 views

For a prime $p\ge 17$ is $\dfrac{p^2-1}{24}$ ever a prime?

4 votes
3 answers
286 views

How difficult exactly is $\int\tan(x^2)\ dx$?

4 votes
2 answers
328 views

Countable order-dense subset in a linear order

4 votes
2 answers
47 views

Do the closed unit disk $D$ and $f(D)$ intersect, if $||f(x)-x||\le2$ for all $x\in D$?

3 votes
1 answer
71 views

Could all iterates of $s(n)=2n+1$ be composite for some starting $n$?

2 votes
1 answer
82 views

A function and its derivative chasing tails

2 votes
1 answer
126 views

Order-preserving bijection from the negative irrationals to the irrationals less than $\pi$

2 votes
2 answers
112 views

Wolfram Alpha numerical errors, integral computation,

2 votes
1 answer
97 views

Are components of complement of a set $S$ always close to $S$

1 vote
2 answers
77 views

For $B$ positive semi-definite matrix find $z\ge0$ with $Bz\ge0$

1 vote
0 answers
55 views

Impossible form of a triangular number