Good Question - Badge - Mathematics Stack Exchange

Good Question

Question score of 25 or more. This badge can be awarded multiple times.

Awarded 7271 times.

Path-Connected implies Connected without knowing that [0,1] is connected

Awarded 8 hours ago

Nils Matthes

4,3843 gold badges23 silver badges47 bronze badges

Interesting infinite product $\sqrt{2}-1=\dfrac{1\cdot7\cdot9\cdot15\cdot17\cdot23\cdots}{3\cdot5\cdot11\cdot13\cdot19\cdot21\cdots}$

Awarded yesterday

Lithium

8301 silver badge11 bronze badges

Is there a function whose autoconvolution is its square? $g^2(x) = g*g (x)$

Awarded yesterday

BigMathGuy

1611 silver badge6 bronze badges

Is there anyone among us who can identify a certain SUS space?

Awarded yesterday

Steven Clontz

3,41115 silver badges26 bronze badges

basic difference between canonical isomorphism and isomorphims

Awarded 2 days ago

MAS

10.2k4 gold badges26 silver badges83 bronze badges

Evaluating $\int_{0}^{\pi/4} \log(\sin(x)) \log(\cos(x)) \log(\cos(2x)) \,dx$

Awarded Sep 30 at 23:57

user 1591719

43.9k12 gold badges102 silver badges253 bronze badges

Why is the definition of "limit" difficult to understand at first?

Awarded Sep 30 at 18:17

Trevor Wilson

16.9k34 silver badges69 bronze badges

Is homology determined by cohomology?

Awarded Sep 29 at 5:45

user101010

5,2031 gold badge11 silver badges32 bronze badges

Gauss-divergence theorem for volume integral of a gradient field

Awarded Sep 28 at 19:20

Mohamed Ouda

3871 gold badge3 silver badges10 bronze badges

Lee, Introduction to Smooth Manifolds Solutions

Awarded Sep 27 at 13:57

Dávid Natingga

2,8092 gold badges26 silver badges40 bronze badges

Notions of stability for differential equations

Awarded Sep 27 at 4:02

Zoltan Berrigomo

2592 silver badges4 bronze badges

What are the ways of proving that the Cantor set is uncountable apart from Cantor diagonalization?

Awarded Sep 27 at 2:08

aaditya

2751 gold badge3 silver badges3 bronze badges

How can we think and/or write rigorously about integration by substitution?

Awarded Sep 27 at 1:27

goblin GONE

66.9k18 gold badges101 silver badges280 bronze badges

How can I improve my problem solving/critical thinking skills and learn higher math?

Awarded Sep 26 at 21:49

Ansh.23

4116 silver badges9 bronze badges

Group formed on Parabola similarly to how an Elliptic curve forms a group (by drawing lines, circles, intersecting, or taking tangent lines)

Awarded Sep 26 at 18:04

TheGhostOfGaussPossessesMe

20.8k7 gold badges47 silver badges101 bronze badges

Dual of $l^\infty$ is not $l^1$

Awarded Sep 25 at 18:16

Benzio

2,0372 gold badges19 silver badges32 bronze badges

What do the cosets of $\mathbb{R} / \mathbb{Q}$ look like?

Awarded Sep 25 at 16:18

Michaela Light

1,27611 silver badges16 bronze badges

Does an injective endomorphism of a finitely-generated free R-module have nonzero determinant?

Awarded Sep 24 at 21:45

Qiaochu Yuan

409k47 gold badges894 silver badges1299 bronze badges

ELI5: Riemann-integrable vs Lebesgue-integrable

Awarded Sep 24 at 17:42

AlphaOmega

5801 gold badge5 silver badges15 bronze badges

Prove homotopic attaching maps give homotopy equivalent spaces by attaching a cell

Awarded Sep 24 at 4:08

Tom

6717 silver badges12 bronze badges

the zeros of $\sin(z)$, where $z$ is a complex number

Awarded Sep 22 at 19:16

user119615

9,9885 gold badges37 silver badges109 bronze badges

Product of connected spaces

Awarded Sep 20 at 4:18

moe

2991 gold badge3 silver badges6 bronze badges

If $A$ is a subset of $B$, then the closure of $A$ is contained in the closure of $B$.

Awarded Sep 20 at 1:21

Daavid M.

2511 gold badge3 silver badges4 bronze badges

Completion of borel sigma algebra with respect to Lebesgue measure

Awarded Sep 19 at 13:33

Blunka

9156 silver badges12 bronze badges

'Intuitive' difference between Markov Property and Strong Markov Property

Awarded Sep 19 at 7:05

Debreu

8041 gold badge7 silver badges17 bronze badges

Where does one learn how to apply categorical algebra and higher abstractions to algebraic topology?

Awarded Sep 18 at 20:26

FShrike

32.7k3 gold badges22 silver badges63 bronze badges

Inverse of an invertible upper triangular matrix of order 3

Awarded Sep 18 at 19:52

Hafiz Temuri

3932 gold badges5 silver badges11 bronze badges

Determinant of rank-one perturbations of (invertible) matrices

Awarded Sep 18 at 16:51

Stefan Smith

7,8822 gold badges40 silver badges61 bronze badges

$C(X)$ is separable when $X$ is compact?

Awarded Sep 17 at 10:10

David Chan

1,92014 silver badges20 bronze badges

Differentiate $f(x)=x^TAx$

Awarded Sep 17 at 10:10

dreamer

3,3398 gold badges48 silver badges74 bronze badges

Series as an integral (sophomore's dream)

Awarded Sep 17 at 9:55

John Cage

2533 silver badges4 bronze badges

Prove $\sum\limits_{\mathrm{cyc}}\sqrt{x^2+yz+2}\ge 6$ for $x, y, z \ge 0$ with $x+y+z=3$

Awarded Sep 17 at 9:55

math110

92.6k16 gold badges132 silver badges495 bronze badges

Is there an expression for $I(n)=\int_{0}^{\frac{\pi}{4}}x\tan^{n}x dx$?

Awarded Sep 17 at 8:17

Kisaragi Ayami

5263 silver badges6 bronze badges

Fibonacci-esque sequences modulo $1$: what is the largest possible infimum?

Awarded Sep 15 at 17:56

mathlander

3,8312 gold badges11 silver badges41 bronze badges

Equation of a rectangle

Awarded Sep 14 at 6:57

Cobold

9094 gold badges13 silver badges23 bronze badges

How to prove the distributive property of cross product

Awarded Sep 14 at 6:33

KunXian Xia

8272 gold badges9 silver badges7 bronze badges

u-substitution shows 0=1

Awarded Sep 13 at 22:52

beanstalk

4993 silver badges8 bronze badges

Really: why is the Kelvin transform harmonic?

Awarded Sep 13 at 22:27

Michele Caselli

6945 silver badges14 bronze badges

Is there an easier way to prove the Fundamental Theorem of Algebra for polynomials with real coefficients?

Awarded Sep 13 at 17:41

jacob78

3832 silver badges7 bronze badges

Why can't you prove the law of the excluded middle in intuitionistic logic (for layman)?

Awarded Sep 11 at 21:48

Lance

3,58027 silver badges50 bronze badges

What practical proofs work in intuitionistic but not minimal logic?

Awarded Sep 11 at 21:20

Eliezer Yudkowsky

3852 silver badges7 bronze badges

What's the connection between derivatives and boundaries?

Awarded Sep 11 at 9:03

Chris Taylor

28.5k6 gold badges84 silver badges123 bronze badges

Convergence/divergence of $\sum\frac{a_n}{1+na_n}$ when $a_n\geq0$ and $\sum a_n$ diverges

Awarded Sep 10 at 12:34

James

2513 silver badges3 bronze badges

Doubt about Taylor series: do successive derivatives on a point determine the whole function?

Awarded Sep 9 at 14:49

David O.

3952 silver badges6 bronze badges

Are $\Bbb R^2\setminus \Bbb Q^2$ and $\Bbb R^2\setminus \Bbb Q^2\cup \{(0,0)\}$ homeomorphic?

Awarded Sep 8 at 12:42

Alessandro Codenotti

12.1k2 gold badges28 silver badges56 bronze badges

Orbit stabiliser theorem as an analogue to first isomorphism theorem

Awarded Sep 7 at 11:34

omnicube

2831 silver badge6 bronze badges

Are there more general spaces than Euclidean spaces to have the Heine–Borel property?

Awarded Sep 6 at 0:18

Tim

46.3k52 gold badges227 silver badges499 bronze badges

What are normal schemes intuitively?

Awarded Sep 5 at 22:06

only

2,64619 silver badges27 bronze badges

difference between implicit and explicit solutions?

Awarded Sep 4 at 13:02

Hafiz

3531 gold badge3 silver badges7 bronze badges

On compactness of the space of probability measures

Awarded Sep 1 at 16:11

0056

2513 silver badges3 bronze badges

Showing a subset of the torus is dense

Awarded Aug 31 at 10:16

Bey

3,8232 gold badges25 silver badges49 bronze badges

Homology in a picture? (Is this picture just metaphorical, or a rigorous example that can be formalized?)

Awarded Aug 30 at 15:48

gwynneth-m.sc.

4691 silver badge6 bronze badges

Distinguished triangle induced by short exact sequence

Awarded Aug 30 at 12:02

Joshua Ruiter

2,93213 silver badges31 bronze badges

Minimum number of straight lines to cover $n \times n$ grid?

Awarded Aug 29 at 13:51

Robin Eriksson

2011 silver badge5 bronze badges

$\lambda-z-e^{-z}=0$ has one solution in the right half plane

Awarded Aug 28 at 1:46

i.a.m

2,36813 silver badges32 bronze badges

Derivative of matrix exponential w.r.t. to each element of the matrix

Awarded Aug 24 at 16:30

darwin rajpal

3631 gold badge3 silver badges4 bronze badges

Why is the orthogonal group $\operatorname{O}(2n,\mathbb R)$ not the direct product of $\operatorname{SO}(2n, \mathbb R)$ and $\mathbb Z_2$?

Awarded Aug 24 at 3:06

Roun

2,9375 gold badges30 silver badges40 bronze badges

Can $1!^2+2!^2+3!^2+\dots+n!^2$ be a perfect power when $n\geq2$?

Awarded Aug 22 at 21:33

Thirdy Yabata

553 silver badges16 bronze badges

What is the least number of concerts needed to be scheduled in order that each musician may listen, as part of the audience, to every other musician?

Awarded Aug 22 at 15:02

Louie

5611 silver badge8 bronze badges

What is $\int_0^1 \left(\tfrac{\pi}2\,_2F_1\big(\tfrac13,\tfrac23,1,\,k^2\big)\right)^3 dk$?

Awarded Aug 21 at 21:51

Tito Piezas III

52.4k7 gold badges110 silver badges270 bronze badges

2 3 4 5

…

122 Next