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Should the first be the last by composition of paths?

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drhab

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Odd primes $\neq5$ divide a integer made up of all $1$s. Ditto for integers coprime to $10$.

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Bill Dubuque

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Prove that every integer $n>0$ with $\gcd(n,10) = 1$ has a multiple that can be written with only the digit $9$.

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Bill Dubuque

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Compute close-form of $\int_0^{\frac\pi2}\frac{dt}{\sin t+\cos t+\tan t+\cot t+\csc t+\sec t}$

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KStarGamer

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There are finitely many ideals containing $(a)$ in a PID

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rschwieb

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Proving the existence of a proof without actually giving a proof

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Pedro Sánchez Terraf

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Every bounded non countable subset of $\mathbb{R}$ has a two-sided accumulation point.

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Brian M. Scott

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Are infinities included in the closure of the real set $\overline{\mathbb{R}}$

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MJD

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What counts as a sequence, and how would we know that it isn't deceiving?

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MJD

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How to tell if a Rubik's cube is solvable?

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Anthony Carapetis

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How to solve the equation $\phi(n) = k$?

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lhf

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A "clean" approach to integrals.

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Giuseppe Negro

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Where is the flaw in this "proof" that 1=2? (Derivative of repeated addition)

Awarded Nov 26 at 19:57

Julian Newman

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Vacuous falsehood - does it exist, and are there examples?

Awarded Nov 26 at 2:47

MJD

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What is the difference between "for all" and "there exists" in set builder notation?

Awarded Nov 26 at 2:41

MJD

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Can inequalities be added the way that equations can be added?

Awarded Nov 26 at 2:41

MJD

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how $1/0.5$ is equal to $2$?

Awarded Nov 25 at 16:34

MJD

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What are imaginary numbers?

Awarded Nov 24 at 17:12

user117

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How to Find the Square Root of Numbers That Aren't Square Numbers

Awarded Nov 23 at 8:21

Philippe Malot

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Illustrative examples of a phenomenon in the logic of mathematical induction

Awarded Nov 22 at 23:56

dtldarek

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Counting bounded integer solutions to $\sum_ia_ix_i\leqq n$

Awarded Nov 22 at 3:50

Evan Chen

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How to express $(\lor,\land)$ multiplication in terms of $(+,\land)$ and $(\oplus,\land)$ multiplication?

Awarded Nov 21 at 20:56

FUZxxl

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Covariant Power set functor

Awarded Nov 21 at 8:09

wchargin

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Modular equations system

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Lord_Farin

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uniform random points on a torus

Awarded Nov 20 at 15:16

prisoner849

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Difference between "essential boundary conditions" and "natural boundary conditions"?

Awarded Nov 20 at 8:27

Qmechanic

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Do "imaginary" and "complex" angles exist?

Awarded Nov 20 at 8:27

rationalbeing

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Picard group of product of spaces

Awarded Nov 19 at 13:17

Georges Elencwajg

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Vladimir Zorich vs Rudin/Pugh/Abbott

Awarded Nov 18 at 23:09

dxb

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Tensor product by UMP. Is this 'embeddable' in the theory of categories?

Awarded Nov 18 at 19:26

drhab

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Geometry of a hyperbolic triangle

Awarded Nov 18 at 16:41

Willemien

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subdifferential rule proof

Awarded Nov 16 at 22:04

dohmatob

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Visual intuition for $\frac{1}{b - a} \int_{a}^{b} u(t) \ \text{d}t \in \overline{\text{co}}(u([a,b]))$

Awarded Nov 16 at 16:26

ViktorStein

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Is composition of regular epimorphisms always regular?

Awarded Nov 16 at 1:17

Vej Kse

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Isomorphisms $\mathbb{Z}/n \mathbb{Z}\cong \mathbb{Z}_n$ and $K[x]/(f)\cong K[x]\bmod f$

Awarded Nov 15 at 19:42

Bill Dubuque

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Integral points on an elliptic curve

Awarded Nov 15 at 0:04

Álvaro Lozano-Robledo

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proof of $p'(x)^2 \geq p(x)p''(x) \text { for all x } \in \Bbb{R}$

Awarded Nov 14 at 20:36

I. J. Kennedy

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Ideal generated by two coprime polynomials in $\mathbb{Z}[x]$

Awarded Nov 14 at 17:50

Zev Chonoles

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Ordering on complex numbers

Awarded Nov 14 at 0:08

James S. Cook

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Complex numbers: $ (\sqrt{3}+ i)^{30} $ to 'a + ib' form

Awarded Nov 13 at 6:41

Jyrki Lahtonen

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Show that 3-regular graph (with Hamiltonian cycle) has chromatic index 3

Awarded Nov 13 at 6:41

SleekPanther

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How to split an integral exactly in two parts

Awarded Nov 13 at 1:49

Giuseppe Negro

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sequential continuity vs. continuity

Awarded Nov 12 at 14:10

Brian M. Scott

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How to find distribution of order statistic

Awarded Nov 11 at 11:16

RRL

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Easy math proofs or visual examples to make high school students enthusiastic about math

Awarded Nov 11 at 2:46

Joseph O'Rourke

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Tensor products of functions generate dense subspace?

Awarded Nov 10 at 11:50

tomasz

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Nice examples of groups which are not obviously groups

Awarded Nov 8 at 18:05

Alexander Gruber♦

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Probability on first hitting time of Brownian motion with drift

Awarded Nov 8 at 16:01

saz

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Convergence of Integral Implies Uniform convergence of Equicontinuous Family

Awarded Nov 8 at 2:42

leo

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Elementary method to prove that $|\overline B_{2n}(x)|\le|B_{2n}|$?

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TravorLZH

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A rare integral involving $\operatorname{Li}_2$

Awarded Nov 7 at 23:51

KStarGamer

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Proof that an integral domain that is a finite-dimensional $F$-vector space is in fact a field

Awarded Nov 6 at 19:06

Georges Elencwajg

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How to divide one number in $\textbf Q(\zeta_8)$ by another?

Awarded Nov 6 at 19:06

Jordi Gutiérrez Hermoso

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Physical interpretation of Laplace transforms

Awarded Nov 6 at 11:50

Theoretical Economist

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Expected time till absorption in specific state of a Markov chain

Awarded Nov 6 at 3:16

Terence Coelho

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When does a homotopy in $\mathbb{C}$ extend to a homotopy in the Riemann sphere?

Awarded Nov 5 at 17:26

Najib Idrissi

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Solving an integral with parameter: $\int_{0}^{\pi/2} \frac{\ln(1+a\cos x)}{\cos x}dx$

Awarded Nov 5 at 3:08

Lai

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Expressing bitwise operations in terms of other functions

Awarded Nov 3 at 22:08

Grzegorz Adam Kowalski

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Series Question: $\sum_{n=1}^{\infty}\frac{n+1}{2^nn^2}$

Awarded Nov 3 at 12:31

Venus

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How do outer products differ from tensor products?

Awarded Nov 3 at 10:46

Wrichik Basu

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