Altruist - Badge - Mathematics Stack Exchange

Altruist

First bounty you manually award on another person's question.

Awarded 1245 times.

Sublattices of rank n of the Boolean algebra and partial orders

Awarded Sep 15 at 7:56

Kandinskij

3,5371 gold badge9 silver badges32 bronze badges

The concept of differential and derivative

Awarded Sep 13 at 18:41

vallev

13316 bronze badges

How to solve the first order ODE

Awarded Sep 3 at 1:18

Gonçalo

4,4282 gold badges8 silver badges23 bronze badges

Integrating $x \sec^2 (x)$

Awarded Aug 26 at 13:40

Petəíŕd The Linux Wizard

515 bronze badges

Is there any perfect square in the sequence $12,123,1234,12345,...$?

Awarded Aug 22 at 21:11

Thirdy Yabata

553 silver badges16 bronze badges

Maximum product of sums of a given array of numbers

Awarded Aug 21 at 23:36

TheJack

49413 bronze badges

Let ABCD be a convex quadrilateral with AD = BC. Show that AD and BC determine congruent angles with the line passing the midpoints.

Awarded Aug 16 at 10:03

Ionela Buciu

44516 bronze badges

Deriving the Oversampling formula

Awarded Aug 14 at 17:51

John.W

3692 silver badges11 bronze badges

$a,b,c\ge 0: a+b+c+abc=4$. Prove that: $\sum_{cyc}\sqrt{\frac{a+b}{c+ab}}\ge 3.$

Awarded Aug 9 at 1:04

Dragon boy

12314 bronze badges

Question on a Gaussian sum and Jacobi sum identity

Awarded Jul 22 at 18:56

Andrés Martínez

6813 silver badges14 bronze badges

Proof that Radius of Convergence Extend to Nearest Singularity

Awarded Jul 21 at 20:16

Sidharth Ghoshal

15.8k8 gold badges41 silver badges95 bronze badges

Rotation matrix in R^3

Awarded Jul 3 at 8:06

Apoorv Mishra

1097 bronze badges

What calculus books should I use to learn more advanced calculus after Stewart's or Larson's book or Thomas' book

Awarded Jun 25 at 11:50

pie

8621 gold badge2 silver badges21 bronze badges

Why is an area preserving diffeomorphism a symplectomorphism (in $R^2$)

Awarded Jun 23 at 16:09

KVO

516 bronze badges

What are some conjectures of your own?

Awarded Jun 20 at 0:21

Joako

1,2151 gold badge6 silver badges28 bronze badges

Non-autonomous linear difference inequation

Awarded Jun 13 at 1:00

metamorphy

38.1k16 gold badges46 silver badges115 bronze badges

Understanding proof that the gradient of a scalar field transforms as a vector under rotations.

Awarded Jun 12 at 17:36

Digitallis

3,0228 silver badges29 bronze badges

Why on average, is $A[j]$ smaller than half of the elements of $A[1\dots j]$

Awarded Jun 10 at 10:05

user51462

5976 gold badges12 silver badges29 bronze badges

Explanation of a proof from Stacks Project: Noetherian ring of formal powers series

Awarded Jun 9 at 15:25

themathandlanguagetutor

1,1296 silver badges16 bronze badges

SDE with stationary Log-normal distribution

Awarded Jun 4 at 18:36

user3277533

811 silver badge9 bronze badges

Let $f(x)=x\sin{(\pi x)}$. Spivak's solution manual seems to imply $f'(0)$ does not exist for this function. Why?

Awarded May 31 at 22:04

jordi

2691 silver badge10 bronze badges

Weak equality equation with a negative fractional Sobolev space.

Awarded May 30 at 19:28

OmnipotentEntity

1,2309 silver badges25 bronze badges

Give an example of function continuous for $x \in (a, b)$ and not differentiable in $a < x_{1} <\dots < x_{n} < b $, but differentiable in intervals.

Awarded May 29 at 10:35

qerty149

11616 bronze badges

Integrating the exponential of distance to a convex bounded set

Awarded May 26 at 19:41

user13243542345452

191 silver badge9 bronze badges

How will the wolf catch the sheep in minimum time?

Awarded May 22 at 17:32

Varun Vejalla

8,6782 gold badges11 silver badges45 bronze badges

Asymptotically uncorrelated sequence converges in distribution to normal distribution?

Awarded May 20 at 17:06

jvc

2,0015 silver badges17 bronze badges

How to rationalize the denominator $\frac{1}{1 + \sqrt[3]{5} - \sqrt[3]{25}}$

Awarded May 19 at 21:02

User

1,6792 silver badges21 bronze badges

Lebesgue integral of a measurable function squeezed between two integrable functions

Awarded May 17 at 6:58

S.H.W

4,4814 gold badges21 silver badges56 bronze badges

Generalizing Poisson's binomial distribution to the multinomial case.

Awarded May 9 at 12:55

AspiringMat

2,2141 gold badge16 silver badges31 bronze badges

A map $\phi:M\rightarrow N$ is smooth if and only if $g\in\mathfrak{F}(N)\implies g\circ\phi\in\mathfrak{F}(M)$

Awarded May 6 at 17:34

Pedro Gomes

3,8334 gold badges31 silver badges75 bronze badges

Solving $\log_2(x+1)+x=2$

Awarded Apr 29 at 16:18

nonuser

4963 silver badges13 bronze badges

Bijective extension of Lipschitz map defined over a dense set

Awarded Apr 29 at 4:55

Anne Bauval

27.1k4 gold badges24 silver badges52 bronze badges

Roots of a set of nonlinear equations $ax + yz = b_1; ay + xz = b_2; az + xy = b_3$

Awarded Apr 21 at 1:36

lone student

14.2k2 gold badges20 silver badges60 bronze badges

(Proof verification) Cohn's Measure Theory Ch 6.2 ex 3: $(\overline{D}\mu)(a)=(\underline{D}\mu)(a)=f(a)$ if $f$ is cont. at $a$

Awarded Apr 15 at 19:50

Seth

2,74514 silver badges18 bronze badges

Maximising the expected sum of random variables below a given threshold

Awarded Apr 12 at 16:18

Cheeku

5199 silver badges21 bronze badges

Apostol's proof of Arzelà's Bounded Convergence Theorem

Awarded Apr 10 at 15:22

Shthephathord23

6261 silver badge16 bronze badges

Evaluate the following series having finite terms

Awarded Apr 7 at 5:16

Sathvik

3,2971 gold badge10 silver badges25 bronze badges

Transformation between space partitions

Awarded Apr 6 at 16:40

Girish Srivatsa

13 bronze badges

The Gamma function is holomorphic on V

Awarded Mar 28 at 9:10

Andromeda

3663 silver badges13 bronze badges

How find this matrix $A=(\sqrt{i^2+j^2})$ eigenvalue

Awarded Mar 15 at 4:22

Edward H

1333 silver badges17 bronze badges

Inequality on the moment generating function of a centered random variable which is bounded above

Awarded Mar 15 at 1:05

Zhanxiong

13.6k1 gold badge25 silver badges54 bronze badges

(post deleted or otherwise unavailable)

Awarded Mar 7 at 8:26

Wilbur

357 bronze badges

Placing an integer's divisors around a circle

Awarded Feb 15 at 21:31

PNT

3,9849 silver badges31 bronze badges

Is there a combination of $a,b,c\in\mathbb{N}$ such that $\forall n\in\mathbb{N}\; \gcd(n^a+b,(n+c)^a+b)=1$?

Awarded Feb 15 at 16:12

Clyde Kertzer

2,7045 gold badges12 silver badges43 bronze badges

When does $|X^n|\leq |k^X|$ without the axiom of Choice?

Awarded Feb 7 at 1:18

ℋolo

9,9482 gold badges16 silver badges41 bronze badges

Why can't an inner product give $ \vec u \cdot \vec v = \|\vec u\|\|\vec v\|\cos(\theta/5) $

Awarded Feb 6 at 14:32

Mahkoe

3541 gold badge9 silver badges20 bronze badges

Rationalize a denominator with 3 nth roots.

Awarded Feb 3 at 19:06

Yajat Shamji

3102 silver badges19 bronze badges

Surface area of intersection of sphere and off-angle cone (Footprint of satellite)

Awarded Jan 28 at 17:40

janmarqz

10.4k4 gold badges25 silver badges41 bronze badges

(post deleted or otherwise unavailable)

Awarded Jan 27 at 7:20

Y. Tamer

1571 silver badge13 bronze badges

Given $p$ prime and $H\le S_p$ s.t. $|H| = p$, show if $H\subseteq N\subseteq S_p$ for some nilpotent subgroup $N$, then $H=N$

Awarded Jan 23 at 17:25

one potato two potato

4,6821 gold badge9 silver badges26 bronze badges

Additivity of Lebesgue integral over union of disjoint sets

Awarded Jan 12 at 15:36

FD_bfa

3,7134 gold badges12 silver badges41 bronze badges

How to evaluate $\int_{0}^{1}\arcsin\left ( x\arccos x \right )\mathrm{d}x$

Awarded Jan 9 at 2:34

phi-rate

2,2623 silver badges23 bronze badges

Show a vector space has no countable basis

Awarded Jan 4 at 0:41

Kai Wang

6733 silver badges13 bronze badges

Continuity of $\frac{x^5-4x^3y^2-xy^4}{(x^2+y^2)^2}$ at (0, 0)

Awarded Dec 22, 2022 at 7:28

insipidintegrator

6,2873 gold badges11 silver badges38 bronze badges

$\int_{0}^{\frac{\pi}{4}}\frac{\tan^2 x}{1+x^2}\text{d}x$ on 2015 MIT Integration Bee

Awarded Dec 21, 2022 at 20:51

Kamal Saleh

4,4901 gold badge5 silver badges29 bronze badges

How many ways can I put m objects into n bins such that at least 1 bin has at least k objects?

Awarded Dec 15, 2022 at 14:42

D S

2,4292 gold badges3 silver badges24 bronze badges

Minimax risk algebra in Pattern Classification by Duda, et. al.

Awarded Dec 13, 2022 at 9:07

IntegrateThis

3,7381 gold badge21 silver badges64 bronze badges

the definition of the area of a surface

Awarded Dec 11, 2022 at 20:21

Pikachu

14 bronze badges

How to Evaluate the Integral? $\int_{0}^{1}\frac{\ln\left( \frac{x+1}{2x^2} \right)}{\sqrt{x^2+2x}}dx=\frac{\pi^2}{2}$

Awarded Dec 4, 2022 at 18:33

Eugen Sunic

81 gold badge8 silver badges17 bronze badges

If $n$ is square-free and $n+1 \mid \sigma(n)$, is $n$ a prime?

Awarded Nov 25, 2022 at 16:11

Peter

82.3k16 gold badges68 silver badges216 bronze badges

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