New posts in proof-writing

Let X be a T1 space, and show that X is normal if and only if each neighbourhood of a closed set F contains the closure of some neighbourhood of F

An interesting algorithm about prime numbers that I thought today

Prove by induction that the number of derangements of length $n$ is $D_n = (n-1)(D_{n-1}+D_{n-2}), n>2$

Show that any metrizable space $X$ is Hausdorff

How to prove or disprove $\forall x\in\Bbb{R}, \forall n\in\Bbb{N},n\gt 0\implies \lfloor\frac{\lfloor x\rfloor}{n}\rfloor=\lfloor\frac{x}{n}\rfloor$.

Topology: Show restriction of continuous function is continuous, and restriction of a homeomorphism is a homeomorphism

Proving that the sequence $a_{n}= \frac{1}{n}$ ($n$ odd) and $\frac{3}{n}$ ($n$ even) converges.

Proof with inequalities

Congruent sets of an arithmetic sequence and a geometric sequence

Proof that $\lim_{m\to\infty}(1+\frac{r}{m})^{mt}=e^{rt}$

Prove that $(a+1)(a+2)...(a+b)$ is divisible by $b!$ [duplicate]

Question about how to interpret arbitrary elements

Prove that the only prime triple is 3, 5, 7 [duplicate]

How to prove $4(n!)>2^{n+2}$ for $ n\geq 4$ with induction [duplicate]

Why is it that when proving trig identities, one must work both sides independently?

Modular Arithmetic - Pirate Problem

Proving area of triangle formed at parallelogram midpoint is 1/4 of the parallelogram?

Proof of the Reverse Triangle Inequality

Proof for $\left\lfloor\frac 1j\left\lfloor\frac nk\right\rfloor\right\rfloor=\left\lfloor\frac n{jk}\right\rfloor$ [duplicate]

$0.101001000100001000001$... is irrational. [duplicate]