Revival - Badge - Mathematics Stack Exchange

Revival

Answer more than 30 days after a question was asked as first answer scoring 2 or more. This badge can be awarded multiple times.

Awarded 23076 times.

Strange algebra among elliptic moments $k^pK^qK^\prime{}^r$

Awarded Sep 25 at 6:50

pisco

19.5k2 gold badges63 silver badges108 bronze badges

Necessary and sufficient conditions for a helix

Awarded Sep 24 at 18:06

whuber

8,8581 gold badge32 silver badges43 bronze badges

Why is a free group action called free?

Awarded Sep 24 at 10:09

Joe

24.1k4 gold badges61 silver badges109 bronze badges

If a linear operator in a Hilbert space preserves weak convergence, it must be continuous

Awarded Sep 24 at 6:57

daw

55.7k2 gold badges46 silver badges88 bronze badges

If $a+b+c=x+y+z=1$ then $\frac{a}{y+z}+\frac{b}{x+z}+\frac{c}{x+y}\geq1+\frac{27}{2}abc$

Awarded Sep 24 at 6:32

River Li

51.4k3 gold badges46 silver badges145 bronze badges

Meaning of "strict adherence"

Awarded Sep 24 at 3:05

Suzet

6,4002 gold badges16 silver badges38 bronze badges

How do you determine $\max(\sin(x)/x)$ without using derivatives?

Awarded Sep 24 at 2:25

Oscar Lanzi

51.2k2 gold badges56 silver badges137 bronze badges

Intuition for partial averaging eqution

Awarded Sep 24 at 1:52

Rainymood

2012 silver badges6 bronze badges

How to understand local extrema for a function at the boundary of a set?

Awarded Sep 23 at 21:23

Digitallis

4,5661 gold badge10 silver badges35 bronze badges

Constructing a Hasse diagram for the lexicographic order on $S_1 \times S_2$

Awarded Sep 23 at 20:18

Arpit

463 bronze badges

Locality of canonical Bregman divergence on dually flat manifolds

Awarded Sep 23 at 18:21

Fábio M.

664 bronze badges

Two dimensional integral gives a volume, but what if I don't deal with distances and volumes?

Awarded Sep 23 at 14:20

user98130

2,77716 silver badges26 bronze badges

Solving Cubic Equations with Lagrange Resolvent?

Awarded Sep 22 at 23:02

Nat Kuhn

3271 silver badge11 bronze badges

Compute surface area

Awarded Sep 22 at 19:58

user170231

27.1k3 gold badges49 silver badges96 bronze badges

Literature on Chern-Weil Theory and the Chern-Gauß-Bonnet Theorem

Awarded Sep 22 at 12:53

A. H.

1016 bronze badges

Principal Ultrafilter implies Isomorphic Ultraproduct

Awarded Sep 21 at 20:04

Michal

466 bronze badges

Matrices - Gaussian Elimination

Awarded Sep 21 at 13:16

Lucien Jaccon

8301 silver badge18 bronze badges

If $a>2b$ then $(a^2)!+b^2≠c^2$ and $4$ is the only square solution to the Brocard's problem

Awarded Sep 21 at 13:06

Hagen von Eitzen

384k33 gold badges381 silver badges687 bronze badges

Partial derivative in O'Neill's book

Awarded Sep 21 at 3:53

Alon

2582 silver badges6 bronze badges

Existence of geodesically convex neighborhoods in semi-Riemannian manifolds.

Awarded Sep 20 at 23:16

Govind Menon

363 bronze badges

If this operator is an isometry, does that imply it is not compact?

Awarded Sep 20 at 22:36

Kadmos

3,8012 gold badges9 silver badges35 bronze badges

$\operatorname{Fr}( p(\overline U) )$ where $p : X \to Y$ is a closed, not necessarily continuous, surjection, and $U \subset X$ is open

Awarded Sep 20 at 22:26

Brian M. Scott

635k57 gold badges831 silver badges1.4k bronze badges

On Saddle point method involving Hypergeometric series.

Awarded Sep 20 at 11:46

mathlove

155k10 gold badges127 silver badges315 bronze badges

Question about an upper bound on $\sum_{j=1}^n\frac 1{a_j}$

Awarded Sep 20 at 7:19

Gerry Myerson

188k14 gold badges237 silver badges410 bronze badges

Extension of Shape operator into a Riemannian manifold

Awarded Sep 19 at 22:30

Roberto Carlos Balcázar Araiza

315 bronze badges

Does Every Axiom Set For Classical Propositional Calculus Have Two Negations, and If So, Why?

Awarded Sep 19 at 20:33

Emil Jeřábek

2,99618 silver badges17 bronze badges

Supremum of the union of countably finite and infinite number of sets

Awarded Sep 19 at 17:46

Rishi

213 bronze badges

Gambler's ruin, probability of loss, infinite turns

Awarded Sep 19 at 17:46

Peter Woolfitt

21.5k6 gold badges59 silver badges93 bronze badges

Proving Handshake Theorem.

Awarded Sep 19 at 11:17

SK19

3,30412 silver badges36 bronze badges

How to translate $(\delta-\varepsilon)$ definition of limit into predicate logic

Awarded Sep 19 at 6:44

Ali Dursun

4971 gold badge3 silver badges13 bronze badges

When to apply PEDMAS in reverse?

Awarded Sep 19 at 0:15

Dan

19.3k3 gold badges30 silver badges55 bronze badges

Restrictions on $n$ for a $(n,k)$ Reed-Solomon code?

Awarded Sep 18 at 16:01

tstdmy

515 bronze badges

Kronecker Product Interpretation

Awarded Sep 18 at 10:20

Markus Scheuer

113k7 gold badges107 silver badges253 bronze badges

Reed-Solomon encoding in GF2?

Awarded Sep 18 at 8:27

tstdmy

515 bronze badges

Proof of Brun's irrationality criteria for sequences.

Awarded Sep 18 at 0:15

Pietro Cosentino

464 bronze badges

How many "prime" rectangle tilings are there?

Awarded Sep 17 at 17:15

SeptaCube

1312 bronze badges

Is the $\exists x$ in $\{f(y):\exists x\ (x,y)\in A\}$ necessary?

Awarded Sep 17 at 14:52

ryang

45.2k16 gold badges96 silver badges207 bronze badges

Chain rule for multi-index notation

Awarded Sep 17 at 13:36

Tauti

462 bronze badges

How large is $f_{\Gamma_{0}}(2)$ in the Fast-Growing Hierarchy?

Awarded Sep 16 at 22:02

Boris Dimitrov

4622 silver badges11 bronze badges

How to compute the limit of this nonlinear recurrence?

Awarded Sep 16 at 7:24

Claude Leibovici

298k55 gold badges131 silver badges326 bronze badges

Is it possible to make this physicists' argument rigorous using distributions?

Awarded Sep 15 at 20:21

Winther

25.5k3 gold badges51 silver badges85 bronze badges

Double integration with $\log$

Awarded Sep 15 at 20:01

user170231

27.1k3 gold badges49 silver badges96 bronze badges

Show that the set of prime ideals of A has minimal element with respect to inclusion

Awarded Sep 15 at 19:23

Bowei Tang

4,6136 gold badges15 silver badges37 bronze badges

Prove $\mathbb{S}^2$ is not diffeomorphic to $\mathbb{S}^1 \times \mathbb{S}^1$

Awarded Sep 15 at 12:33

doetoe

4,18723 silver badges29 bronze badges

Prove that $\sum\limits_{cyc}\frac{a}{a^2+ab+b^2+3}\leq\frac{1}{2}$

Awarded Sep 15 at 11:32

Andreas

16.7k28 silver badges64 bronze badges

How may we cahracterize the closed sets of the product topology?

Awarded Sep 15 at 7:42

ducksforever

5703 silver badges11 bronze badges

Taft Hopf Algebra is self dual

Awarded Sep 15 at 0:33

darij grinberg

19.7k4 gold badges49 silver badges95 bronze badges

Computing $\sum_{n=1}^\infty\frac{(-1)^{n-1}H_n^{(2)}}{(2n+1)^4}$

Awarded Sep 14 at 9:31

Jorge Layja

Evaluate $\sum _{n=1}^{\infty }\frac{(-1)^{n-1}H_n\overline{H}_n^2}{n}$ and $\sum _{n=1}^{\infty }\frac{(-1)^{n-1}H_n\overline{H}_n^2}{n^2}$

Awarded Sep 14 at 5:21

Jorge Layja

Number theory: show that ${ 1^2, 2^2, 3^2,... , m^2}$ cannot be a complete residue system

Awarded Sep 14 at 2:32

Bart Michels

27.2k6 gold badges60 silver badges125 bronze badges

$W^{1,1}(\mathbb{R}^n)$ is not compactly embedded in $L^1(\mathbb{R}^n)$?

Awarded Sep 13 at 16:22

Besfort

6323 silver badges7 bronze badges

An error in a generalization of Viviani's theorem in the literature. Asking for a source for a construction.

Awarded Sep 13 at 16:05

Mohammad Mahdi Nasimi

315 bronze badges

Tesselation Combinatorics Problem

Awarded Sep 13 at 12:53

mlg

3622 silver badges13 bronze badges

Derived functors of abelian categories via model categories.

Awarded Sep 13 at 9:33

Jackozee Hakkiuz

6,1791 gold badge18 silver badges39 bronze badges

Let $a:[0,\infty) \to \mathbb R$ is continuous function.Consider the ODE $y'(x)=a(x)y(x),x>0, y(0)=y_0 \ne0.$ Then which of the following are true?

Awarded Sep 13 at 4:07

nmasanta

9,69025 gold badges29 silver badges58 bronze badges

Prove that $\sum\limits_{cyc}\frac{a}{a^2+ab+b^2+3}\leq\frac{1}{2}$

Awarded Sep 12 at 12:42

Michael Rozenberg

Can a discrete function have an asymptote?

Awarded Sep 12 at 9:01

ˈjuː.zɚ79365

3,1541 gold badge39 silver badges155 bronze badges

$\text {dom}(R)$ and $\text {ran}(R)$ exists for any definition of order pair.

Awarded Sep 12 at 7:36

Alberto Takase

3,6211 gold badge15 silver badges27 bronze badges

Show that $f(z) = |z|$ is not differentiable anywhere.

Awarded Sep 12 at 7:36

José Carlos Santos

443k350 gold badges300 silver badges501 bronze badges

Definition of meromorphic function on complex manifolds

Awarded Sep 12 at 5:33

Z Wu

2,57912 silver badges20 bronze badges

Prev 1

…

3 4

6 7

…

385 Next