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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
general-topology
proof-writing
proof-explanation
separation-axioms
An interesting algorithm about prime numbers that I thought today
number-theory
proof-verification
proof-writing
prime-numbers
algorithms
Prove by induction that the number of derangements of length $n$ is $D_n = (n-1)(D_{n-1}+D_{n-2}), n>2$
combinatorics
proof-verification
proof-writing
Show that any metrizable space $X$ is Hausdorff
general-topology
metric-spaces
proof-writing
separation-axioms
How to prove or disprove $\forall x\in\Bbb{R}, \forall n\in\Bbb{N},n\gt 0\implies \lfloor\frac{\lfloor x\rfloor}{n}\rfloor=\lfloor\frac{x}{n}\rfloor$.
algebra-precalculus
proof-writing
proof-explanation
ceiling-and-floor-functions
Topology: Show restriction of continuous function is continuous, and restriction of a homeomorphism is a homeomorphism
general-topology
functions
proof-verification
proof-writing
proof-explanation
Proving that the sequence $a_{n}= \frac{1}{n}$ ($n$ odd) and $\frac{3}{n}$ ($n$ even) converges.
convergence-divergence
proof-writing
Proof with inequalities
proof-writing
Congruent sets of an arithmetic sequence and a geometric sequence
elementary-set-theory
proof-writing
quadratics
arithmetic-progressions
geometric-progressions
Proof that $\lim_{m\to\infty}(1+\frac{r}{m})^{mt}=e^{rt}$
limits
proof-writing
Prove that $(a+1)(a+2)...(a+b)$ is divisible by $b!$ [duplicate]
proof-writing
induction
divisibility
factorial
Question about how to interpret arbitrary elements
discrete-mathematics
proof-writing
Prove that the only prime triple is 3, 5, 7 [duplicate]
proof-writing
How to prove $4(n!)>2^{n+2}$ for $ n\geq 4$ with induction [duplicate]
proof-writing
induction
Why is it that when proving trig identities, one must work both sides independently?
trigonometry
proof-writing
learning
Modular Arithmetic - Pirate Problem
proof-writing
modular-arithmetic
Proving area of triangle formed at parallelogram midpoint is 1/4 of the parallelogram?
geometry
proof-writing
Proof of the Reverse Triangle Inequality
real-analysis
proof-verification
metric-spaces
proof-writing
alternative-proof
Proof for $\left\lfloor\frac 1j\left\lfloor\frac nk\right\rfloor\right\rfloor=\left\lfloor\frac n{jk}\right\rfloor$ [duplicate]
elementary-number-theory
proof-writing
ceiling-and-floor-functions
$0.101001000100001000001$... is irrational. [duplicate]
real-analysis
proof-writing
rationality-testing
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