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Interesting 20 Bountied Hot Week Month
9 votes
7 answers
15k views

Why is $ \sum_{n=0}^{\infty}\frac{x^n}{n!} = e^x$?

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voidranjer
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0 votes
1 answer
1k views

Approach to solving underdetermined nonlinear system of equations

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CommunityBot
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1 vote
9 answers
136 views

Is there a "natural" example of a poset that is not a lattice?

bof's user avatar
bof
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1 vote
0 answers
20 views

Why can’t the derivative proof for $\sum (i+1)(i+2)x^i$ be applied directly to a specific $x$?

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Math12
  • 839
126 votes
38 answers
13k views

"Almost true": non-trivial claims that have exactly one counterexample

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Carlyle
  • 3,958
0 votes
2 answers
29 views

A non valid triangulation on the torus

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Ben Steffan
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0 votes
0 answers
14 views

Convolution with "good kernels" is $L^p$ convergent?

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user760
  • 3,012
5 votes
0 answers
71 views

Triangle center dividing it in three quadrilaterals of the same area

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Hosam Hajeer
  • 258
1 vote
1 answer
21 views

Find Angle in Isosceles Triangle with Constructions Involving Circumcenter and Reflections

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Intelligenti pauca
  • 57k
0 votes
0 answers
8 views

Example where the limit defining topological entropy via separated sets does not exist

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Kariuki
  • 163
0 votes
1 answer
45 views

Prediction of term asymptotic from sum asymptotic.

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Bruno Andrades
  • 5,646
-3 votes
1 answer
38 views

Can a rational function like this be integrated?

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StephenG - Help Ukraine
  • 767
0 votes
0 answers
12 views

Solve the equation $a^{\,\log_{2b}\!\left(x+\frac{b}{x}\right)} = \frac{(a+2b)x - b^{2} - x^{2}}{x}, $

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Pam Munoz Ryan
  • 405
2 votes
0 answers
17 views

Parametrization of integer solutions to a Diophantine equation yielding a perfect square

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Jan Eerland
  • 29.7k
7 votes
1 answer
148 views

How many points are needed to cover a whole lattice?

Eric Einer's user avatar
Eric Einer
  • 11
2 votes
1 answer
264 views

$\Omega^1_{k[[X]]/k}$ is not finitely generated over $k[[X]]$

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hm2020
  • 10.4k
31 votes
3 answers
2k views

Does Birkhoff - von Neumann imply any of the fundamental theorems in combinatorics?

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Mike Earnest
  • 86.1k
4 votes
1 answer
279 views

Does anything deeper hide behind this inequality?

Martin R's user avatar
Martin R
  • 133k
1 vote
1 answer
85 views

Check the correctness of these entailments (a use of the Deduction Theorem)

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Tankut Beygu
  • 4,959
1 vote
1 answer
755 views

dimension of intersection of subspaces in $\Bbb R^4$

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1 vote
1 answer
171 views
+50

Replace a random variable by a "small" Gaussian

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tituf
  • 943
0 votes
0 answers
33 views

the limit of a function

A12345's user avatar
A12345
  • 823
13 votes
3 answers
623 views

Die dilemma: get paid the sum or go home

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enryuxbt
  • 65
4 votes
2 answers
89 views

Probability of random 5-degree polynomial has double integer roots (1,1)

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josh
  • 185
12 votes
0 answers
404 views

Convergence of Laplace transform

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Srini
  • 2,430
1 vote
1 answer
65 views

Help computing two regions for multivariable calculus

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user170231
  • 27.1k
1 vote
1 answer
25 views

Justifying $ y \cdot f\left(a \right) = (x) \cdot f\left(A \right) \cdot (\alpha)$ for $a\in R$ integral, $C \subseteq R$ integral domain extension

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hm2020
  • 10.4k
0 votes
2 answers
757 views

Matrices and unique and infinite solutions

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CommunityBot
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3 votes
2 answers
160 views

What is the shortest way to write an equivalent relation between n number of elements assuming that the transitive property is invalid.

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mezzoctane
  • 1,889
0 votes
0 answers
64 views

If $f$ is non-constant, holomorphic and has a zero, then there's a neighbourhood where $f$ and $f'$ don't vanish

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MrGran
  • 1,118
0 votes
1 answer
52 views

Will one big ball of ice melt at the same rate as many small balls of ice (assuming they both have the same volume)?

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naturallyInconsistent
  • 689
3 votes
1 answer
230 views

Proving $\sup(A)+\sup(B)=\sup(A+B)$

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Anne Bauval
  • 51.3k
2 votes
3 answers
134 views

Question such that heuristics suggest $f(n) \mid g(n)$ infinitely but $f(n) \nmid g(n)$ for all $n \in \mathbb{N}$

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btilly
  • 3,473
2 votes
0 answers
132 views

Is this the simplest proof that $\mathbb{R}^k$ and $\mathbb{H}^k$ are not homeomorphic?

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David Gao
  • 25.8k
0 votes
1 answer
143 views

Prove: If $A + B = \{a + b \mid a \in A, b \in B \}, \text{ then }\sup (A + B) = \sup (A) + \sup (B)$, where $A,B$ are bounded sets in $\mathbb{R}$

Anne Bauval's user avatar
Anne Bauval
  • 51.3k
1 vote
1 answer
124 views
+50

Understanding distributions in "An Introduction to Quantum Field Theory" by George Sterman

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Qmechanic
  • 13.4k
3 votes
1 answer
153 views

Divide a right triangle into three quadrilaterals of equal area

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mezzoctane
  • 1,889
0 votes
0 answers
54 views

About the definiton of the limit of functions in $\mathbb R$

A12345's user avatar
A12345
  • 823
4 votes
3 answers
8k views

Proving sup(A + B) = sup A + sup B

Anne Bauval's user avatar
Anne Bauval
  • 51.3k
0 votes
1 answer
84 views

Does the iteration of the function $N=2^{k+1}\cdot m-1$ (where $m=\frac{2^{t}\cdot n+1}{3^{k+1}}$) eventually produce all odd multiples of 3?

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mezzoctane
  • 1,889
1 vote
0 answers
29 views

Farb & Dennis Corollary to Nakayama's Lemma: When surjectivity modulo J(R) implies surjectivity

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chris
  • 11
2 votes
1 answer
63 views

Understanding a proof in Milne's notes on algebraic geometry

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Ito Yukis
  • 1,080
0 votes
0 answers
31 views

Finding the extrema

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Gia Khang
  • 19
4 votes
2 answers
3k views

Reconstructing a function from its critical points and inflection points

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Dimitrios ANAGNOSTOU
  • 332
0 votes
2 answers
761 views

An Efficient Minimum Distance Bipartite Matching Algorithm

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Simon Goater
  • 881
1 vote
1 answer
750 views

Transition probability matrix update

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  • 1
0 votes
0 answers
42 views

Proof of a continuous map $h:S^1 \to X$ is nullhomotopic iff $h_*$ is trivial homomorphism without lifting

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khashayar
  • 2,674
6 votes
3 answers
711 views

Fubini-Study metric/form

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Fungaria
  • 125
1 vote
0 answers
37 views

Problem 3 of part b of 4.5.1 of Evans' PDE

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K.defaoite
  • 14.3k
4 votes
3 answers
422 views

Prove $\frac{a^2}{b^2} + \frac{b^2}{c^2} + \frac{c^2}{a^2} \ge \frac{b}{a} +\frac{c}{b} +\frac{a}{c}$ for any three positive reals $a,b,c.$

Átila Correia's user avatar
Átila Correia
  • 19.6k
2 votes
1 answer
93 views

Doubting Spivak's proof that $\sup(A)+\sup(B)\le\sup(A+B)$ (Chapter 8, Problem 13)

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Asaf Karagila♦
  • 408k
0 votes
1 answer
29 views

Is there a general rule for finding the general formula based on recurring sequences?

user1707130's user avatar
user1707130
  • 1
2 votes
1 answer
75 views

Are there infinitely many odd composite numbers with digit-disjoint factorizations?

JOrE's user avatar
JOrE
  • 136
3 votes
1 answer
77 views

Prove that the sum of concatenation of all nonzero single digits (except $0$ in base 1) in first $2026$ bases is not a square

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Adam AbdulAlim
  • 56
0 votes
0 answers
54 views

Confusion regarding Tangent Basis

Fin H's user avatar
Fin H
  • 107
0 votes
0 answers
40 views
+50

Relation between cuts of ellipsoid by lines and the ellipsoid itself

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Raul Fernandes Horta
  • 1,840
3 votes
0 answers
86 views

How to recover an affine group scheme

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NoetherNerd
  • 775
1 vote
1 answer
1k views

Finding the volume between a paraboloid and plane.

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user170231
  • 27.1k
-1 votes
0 answers
35 views

Almost Harmonic Mean Inquality

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azqwa
  • 1
1 vote
1 answer
54 views

Non orientability of a manifold

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Lourenco Entrudo
  • 2,389
0 votes
0 answers
11 views

Graph enumeration based on unlabelled pairwise distance distribution of vertices

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jercai
  • 135
1 vote
1 answer
83 views

Understanding Achim Klenke's Probability Theory, Proof of Theorem 15.34

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Series Enjoyer
  • 116
7 votes
2 answers
259 views

Find minimum of $\sum\limits_{i=1}^{n}a^2_{i}-2\sum\limits_{\mathrm{cyc}} a_1 a_2$ subject to $\sum\limits_{i=1}^n a_i = 1$

Sangchul Lee's user avatar
Sangchul Lee
  • 186k
0 votes
0 answers
22 views

Worst Case "Uniformization" of Probability Distribution

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Joseph Expo
  • 668
2 votes
1 answer
2k views

Prove that the cross ratio of four distinct points is real iff the four points lie on single Euclidean line or circle

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CommunityBot
  • 1
1 vote
1 answer
40 views

Collinearity of $M', H, N'$ where $M', N'$ are reflections of midpoints across sides of the intouch triangle

sirous's user avatar
sirous
  • 13.8k
7 votes
0 answers
111 views
+300

Specific invariants for cyclic groups in Galois theory

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Simón Flavio Ibañez
  • 605
0 votes
1 answer
52 views

Finding rotations transform

azerbajdzan's user avatar
azerbajdzan
  • 1,277
0 votes
0 answers
11 views

LDL decomposition when D has different size

lurscher's user avatar
lurscher
  • 739
0 votes
1 answer
57 views

clarification about second derivative test on the real functions

btilly's user avatar
btilly
  • 3,473
2 votes
1 answer
64 views

Bounding the difference between the ground state energy of a Hamiltonian and the expectation of the Hamiltonian

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Rodrigo de Azevedo
  • 23.7k
1 vote
2 answers
760 views

Prove row space of RREF equals row space of matrix

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CommunityBot
  • 1
4 votes
1 answer
99 views

Does uniform convergence on compact subsets of $\mathbb{R}$ imply weak convergence in $L_p(\mathbb{R})$?

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Dean Miller
  • 9,377
0 votes
0 answers
10 views

Convergence in distribution to stationary SDE solution

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Raven the Raven
  • 1
2 votes
2 answers
73 views

Erdős Problem 943 (and its Lean formalisation)

Daphne E's user avatar
Daphne E
  • 21
5 votes
1 answer
317 views

Prove $\frac{a^2}{b} + \frac{b^2}{c} + \frac{c^2}{d} + \frac{d^2}{a} \ge \sqrt{4(p^2 - 2q) + 8\left(p^2 - \frac83q\right)}$

River Li's user avatar
River Li
  • 51.4k
4 votes
1 answer
77 views

A contest problem about Tic-Tac-Toe

Especially Lime's user avatar
Especially Lime
  • 47.8k
2 votes
3 answers
154 views

Probability question on drawing balls

true blue anil's user avatar
true blue anil
  • 49.8k
0 votes
1 answer
21 views

Length of submodules in a cyclic uniserial module

Leobeth's user avatar
Leobeth
  • 2,953
2 votes
1 answer
43 views

Lebesgue measure on $\mathbb{R}^d$ as a tempered distribution

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Raul Fernandes Horta
  • 1,840
0 votes
0 answers
14 views

Hypothesis testing with a sample from a shifted exponential distribution (Jun Shao - Mathematical Statistics, exercise 6.20, point (v))

Fran712's user avatar
Fran712
  • 467
4 votes
1 answer
747 views

Prove that $N(Z;Y)$ is trivial if and only if there exists a set of $k$ independent functions $g_1,…,g_k$ for $Z$ on some set $U$ in $Y$.

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CommunityBot
  • 1
2 votes
1 answer
57 views

How to find Farkas certificates?

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Rodrigo de Azevedo
  • 23.7k
0 votes
0 answers
17 views

is there software that can generate graphs from sets of points for Euclidean graph theory?

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Samuel Loly
  • 1
3 votes
1 answer
103 views

Relative singular homology of the pair $(\mathbb{R},\mathbb{R}-\{0\})$

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Tuhin Subhra Mukherjee
  • 553
0 votes
0 answers
18 views

Problem 2 of part b of 4.5.1 of Evans' PDE

Enhao Lan's user avatar
Enhao Lan
  • 6,976
0 votes
0 answers
32 views

Problem 1 of part b of 4.5.1 of Evans' PDE

Enhao Lan's user avatar
Enhao Lan
  • 6,976
7 votes
3 answers
2k views

If ${a}$ is an arbitrary integer, then prove that ${360|a^2(a^2-1)(a^2-4)}$.

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Bill Dubuque
  • 285k
0 votes
1 answer
18 views

Construction of a totally positive set in Hahn decomposition theorem

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Kavi Rama Murthy
  • 362k
1 vote
2 answers
60 views

About the relationship between flatness as $R$-module of an ideal $K$ of a commutative ring $R$ and the flatness of the quotient $R/K$

TY Mathers's user avatar
TY Mathers
  • 20.8k
4 votes
0 answers
102 views
+250

Over $\mathbb R^2$, given a tool that can $n$-sect an angle for any $n$, for which $n$ can you construct the $n$th root of any given $x > 0$?

Sunny's user avatar
Sunny
  • 124
1 vote
1 answer
60 views

Possible game states of card game Naishi

HighDiceRoller's user avatar
HighDiceRoller
  • 1,280
1 vote
1 answer
188 views

Why does Fermat's little theorem not hold for all composite numbers?

Gerry Myerson's user avatar
Gerry Myerson
  • 188k
0 votes
1 answer
41 views

Showing positive definite quadratic forms give the "most symmetrical" metrics over $\mathbb{R}^n$

walldrum's user avatar
walldrum
  • 101
4 votes
6 answers
345 views

Show that $\sum\limits_{n=1}^{\infty}\frac{(H_{n})^2}{n(n+1)}=3\zeta(3)$, where, for every positive $n$, $H_n=\sum\limits_{k=1}^n\frac1k$

FDP's user avatar
FDP
  • 16.2k
2 votes
1 answer
1k views

Primary Rational Canonical form Matrix

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