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Top Questions
85
votes
What my dog really hears
code-golf
string
substitution
asked May 9 '17 at 8:07
codegolf.stackexchange.com
46
votes
How can “[” be an operator in the PHP language specification?
php
specifications
asked Jan 9 '16 at 14:42
stackoverflow.com
36
votes
A circle in the plane contains at most four lattice points?
euclidean-geometry
asked Jul 30 '15 at 20:55
math.stackexchange.com
31
votes
Smallest order for finite group that needs many elements to generate it
group-theory
finite-groups
asked Nov 2 '11 at 13:10
math.stackexchange.com
27
votes
Divisibility property for sequence $a_{n+2}=-2(n-1)(n+3)a_n-(2n+3)a_{n+1}$
sequences-and-series
modular-arithmetic
recurrence-relations
asked Apr 8 '18 at 16:16
math.stackexchange.com
20
votes
Comparing countable models of ZFC
logic
set-theory
model-theory
asked Sep 13 '11 at 4:35
math.stackexchange.com
20
votes
Why is $(\sqrt{2}+\sqrt{3})^{2008}$ so close to an integer?
number-theory
algebraic-number-theory
approximation-theory
asked Jun 9 '14 at 19:41
math.stackexchange.com
18
votes
Is $SO_n({\mathbb R})$ a divisible group?
linear-algebra
group-theory
lie-groups
divisible-groups
asked Dec 19 '13 at 6:23
math.stackexchange.com
18
votes
Square root of positive definite nonsymmetric matrix
linear-algebra
matrices
asked Feb 10 '14 at 7:24
math.stackexchange.com
17
votes
Are there statements that are undecidable but not provably undecidable
logic
set-theory
asked Sep 17 '11 at 9:12
math.stackexchange.com
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Top Answers
30
Interesting Olympiad Style Problem about Invariance
math.stackexchange.com
28
Is it possible for an irreducible polynomial with rational coefficients to have three zeros in an arithmetic progression?
math.stackexchange.com
25
How to prove that minimum of two exponential random variables is another exponential random variable?
math.stackexchange.com
25
Does there exist rational $a,b,c$, such that $\sqrt[3]{1}+\sqrt[3]{2}+\sqrt[3]{4}=\sqrt[3]{a}+\sqrt[3]{b}+\sqrt[3]{c}$
math.stackexchange.com
20
Let $a_{i} \in\mathbb{R}$ ($i=1,2,\dots,n$), and $f(x)=\sum_{i=0}^{n}a_{i}x^i$ such that if $|x|\leqslant 1$, then $|f(x)|\leqslant 1$. Prove that:
math.stackexchange.com
17
Example of two dependent random variables that satisfy $E[f(X)f(Y)]=Ef(X)Ef(Y)$ for every $f$
math.stackexchange.com
15
Prove that $2^n-3$ is squarefree
math.stackexchange.com
14
$f(x)$ with real co-efficient and degree 2011 there is a real number $b$ such that $f(b)=f'(b)$
math.stackexchange.com
13
Galois group of a biquadratic quartic
math.stackexchange.com
13
convergence in probability induced by a metric
math.stackexchange.com
13
Prove that $\phi(n) \geq \sqrt{n}/2$
math.stackexchange.com
13
what is the sum of this?$\frac12+ \frac13+\frac14+\frac15+\frac16 +\dots\frac{1}{2012}+\frac{1}{2013} $
math.stackexchange.com
12
symplectic lie algebra is simple
math.stackexchange.com
12
When is a sum of consecutive squares equal to a square?
math.stackexchange.com
12
How to represent Fermat number $F_n$ as a sum of three squares?
math.stackexchange.com
11
Algebra Iranian Olympiad Problem
math.stackexchange.com
11
How find this determinant $\det(\cos^4{(i-j)})_{n\times n}$
math.stackexchange.com
11
How to find the eigenvalues and Jordan canonical form of this matrix
math.stackexchange.com
11
Prove:$A B$ and $B A$ has the same characteristic polynomial.
math.stackexchange.com
10
Does $2x^2-1=y^5$ have a solution in integers, with $y>1$?
math.stackexchange.com
10
Understanding the proof of Schur-Weyl Duality
math.stackexchange.com
10
Integers expressible in the form $x^2 + 3y^2$
math.stackexchange.com
10
Is $\ a^b+b^a\ $ transcendental if $\ a^b\ $ and $\ b^a\ $ are?
math.stackexchange.com
10
How does (21) factor into prime ideals in the ring $\mathbb{Z}[\sqrt{-5}]$?
math.stackexchange.com
10
Find the value of $a+b+c$
math.stackexchange.com
10
Prove that $g(x)=\frac{\ln(S_n (x))}{\ln(S_{n-1}(x))}$ is increasing in $x$, where $S_{n}(x)=\sum_{m=0}^{n}\frac{x^m}{m!}$
math.stackexchange.com
10
Polynomials invariant under the action of $S_m \times S_n$
math.stackexchange.com
10
If $[L:k]$ is odd, $f$ quadratic form over $k$, then $\exists$ zero in $k$ when $\exists$ zero in $L$
math.stackexchange.com
10
Show that $P_i$ and $\sum_i P_i$ being idempotent implies $P_i P_j=\delta_{ij}$
math.stackexchange.com
9
Find rank of the matrix $a_{ij}=(i-j)^2$, $i,j=1,\dots, n$
math.stackexchange.com
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