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mm-aops
  • Member for 9 years, 2 months
  • Last seen more than 3 years ago
29 votes
Accepted

Union of two $\sigma$-algebras is not $\sigma$-algebra

15 votes
Accepted

For $x\in\mathbb R\setminus\mathbb Q$, the set $\{nx-\lfloor nx\rfloor: n\in \mathbb{N}\}$ is dense on $[0,1)$

11 votes

how to prove that $n(n+1)$ can't be square?

10 votes
Accepted

Need to prove that the equation has only 1 solution.

8 votes

Additive but not $\sigma$-additive function

7 votes

Prove that when $f(A) \subseteq f(B)$ doesn't always mean that $A \subseteq B$

7 votes
Accepted

proving $\lim\limits_{n\to\infty} \int_{0}^{1} f(x^n)dx = f(0)$ when f is continous on [0,1]

7 votes
Accepted

Möbius band with its middle part removed is still connected

6 votes
Accepted

Does continuity of $f$ imply $f^{-1}(\bar A)\subset\overline{f^{-1}(A)}$?

6 votes
Accepted

Flag making with 6 vertical stripes

6 votes

Math Olympiad Algebraic Question

5 votes
Accepted

Recursive formula for the probability that the starting player wins [DBertsekas & JTsitsiklis P57, 1.21]

5 votes

Help solving the limit $\lim_{n \to \infty} \frac{2^{\ln n}}{n^3}$

5 votes

If a series of reals is convergent, must the series of their cubes also be convergent?

5 votes

non empty set with empty interior is countable at most

5 votes

$1, e^{ix}, e^{-ix}$ are linearly independent

4 votes

Help with a proof

4 votes
Accepted

Characterisation of norm convergence

4 votes

Proving $ f (z)=5$ for all $ z \in \mathbb {C} $

4 votes
Accepted

Every subgroup of a group is normal

4 votes
Accepted

how can we get from $x \equiv 4 \pmod 9$ to $x \equiv 1 \pmod 3$

4 votes

combinational proof for $ 1 + 2 + \cdots + n = \binom {n+1} 2 $

3 votes

Using the product rule to show that $(fgh)' = f 'gh + fg' h + fgh' $

3 votes

Prove by induction that $n < 2^n$ for all $n \ge 1$

3 votes

Lebesgue integral is 0

3 votes

Squeeze Theorem when the sin parameter is a fraction

3 votes
Accepted

Prove that any monotonic and bijective function is an homeomorphism with the usual topology

3 votes

Prove that there exists a $x$ such that $c<x<b$ and $f(x)>f(c)$.

3 votes

how can we compute this result?

3 votes
Accepted

Proof that the derivative of a linear function is $0$.