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Interesting 9 Bountied Hot Week Month
3 votes
3 answers
6k views

Repeatedly summing digits, casting out nines, digital root

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Bill Dubuque
  • 285k
0 votes
0 answers
21 views

Correspondence Local Systems & $\Bbb Z \pi_1(A)$-modules and its Compatibility

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user267839
  • 10k
0 votes
0 answers
2 views

Grothendieck spectral sequence for right exact functors?

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coconuthead
  • 139
1 vote
2 answers
104 views

Magnetic Field of Cylinder with Uniform Current Density

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Semiclassical
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1 vote
0 answers
31 views

Conversion between Cartier Divisors, Weil Divisors, Line Bundles and Invertible Sheaves.

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William
  • 71
3 votes
2 answers
785 views

Compact Lie subgroup of $GL_n(\mathbb{R})$

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hbghlyj
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0 votes
0 answers
9 views

Find Optimal Effort Level

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lulu
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54 votes
7 answers
116k views

What is the difference between Average and Expected value?

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Aqua
  • 101
3 votes
1 answer
65 views

How many components does an arc meet in a continuum

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Aldo
  • 139
0 votes
1 answer
33 views

If $K/F$ and $L/F$ are separable, then the composite $KL/F$ is separable

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hdecristo
  • 1,167
1 vote
2 answers
783 views

Show that a differential equation has a particular solution?

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CommunityBot
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8 votes
3 answers
540 views

Integral $\int_0^{\infty} \arctan{\left(\frac{n}{\cosh{(x)}}\right)} \mathop{dx}$

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Quanto
  • 124k
0 votes
0 answers
21 views

Prove for all $n \in \mathbb{N}, \int_{0}^{1}(f(x))^{n+1}dx \geq \int_{0}^{1} x^n f(x)dx$

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PSW
  • 327
1 vote
1 answer
66 views

Prove that $\int_0^1\operatorname{Li}_2\left(\frac{1-x^2}{4}\right)\frac{2}{3+x^2}\,\mathrm dx= \frac{\pi^3 \sqrt{3}}{486}$

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Sangchul Lee
  • 185k
2 votes
0 answers
43 views

Does Blaschke’s characterization of ellipsoids extend to non-compact convex body?

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hbghlyj
  • 6,009
0 votes
1 answer
385 views

Conversion base $r$ to base $10$ (decimal) algorithm

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Gonçalo
  • 16.5k
3 votes
2 answers
77 views

What is the correct definition of a limit point in real analysis?

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Matthew Leingang
  • 28k
0 votes
1 answer
59 views

Proof that $F$ is an algebra over $\Bbb R$

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Wrlord
  • 2,099
-1 votes
1 answer
57 views

Finding the real part of some complex number using elementary functions

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wjmolinam
  • 6,445
1 vote
1 answer
2k views

$F(x,y)=2x^4-3x^2y+y^2$. Show that $(0,0)$ is local minimum of the Reduction of F for every linear line that passes through $(0,0)$.

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CommunityBot
  • 1
2 votes
3 answers
165 views
+50

Prove $AF, BC, GE$ are concurrent in a tangent–circumcircle configuration

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D S
  • 5,832
2 votes
3 answers
7k views

Difference between Direction cosine matrix (DCM) and rotation matrix

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M Marques
  • 1
3 votes
3 answers
74 views

Stuck on part (b) of Rising Run Lemma exercise

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Louis
  • 1,154
0 votes
0 answers
24 views

Error in derivation of quaternion derivative

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AeroMain27
  • 333
-1 votes
0 answers
39 views

Gaussian Integral solved with complex integration

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Mitsuki Koga
  • 1
0 votes
2 answers
10k views

In how many ways can the letters of the word ARRANGEMENTS be arranged? A)Probability arrangement begin with EE. B)Probability consonants are together.

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true blue anil
  • 49.6k
1 vote
1 answer
773 views

Economics Application of Rates of Change

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CommunityBot
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22 votes
6 answers
1k views

Why is this angle always less than $49°$?

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Ataulfo
  • 33.6k
3 votes
1 answer
514 views

No eigenvalue of a graph is larger than the maximum degree

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minh quý lê
  • 285
0 votes
1 answer
35 views

Axiomatization similarities between Naturals and Magnitudes

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Noah Schweber
  • 264k
3 votes
2 answers
107 views

In the Pell's equation $a^2-2b^2=1$, is $a$ always of the form $k^2\pm 1$?

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J. W. Tanner
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9 votes
3 answers
172 views

Evaluate: $4^9-\binom{8}{1}4^8+\binom{7}{2}4^7-\binom{6}{3}4^6+\binom{5}{4}4^5$

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minh quý lê
  • 285
121 votes
7 answers
48k views

What would base $1$ be?

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MJD
  • 68k
4 votes
1 answer
42 views

Known properties of these generalized Cauchy distributions

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van der Wolf
  • 6,213
1 vote
0 answers
39 views

Proof of Nagell's Theorem

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m_lovric513
  • 503
3 votes
0 answers
52 views

The exact meaning of ‘subject to that’ in this context

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Rócherz
  • 4,281
4 votes
1 answer
78 views

Quotient group technicality

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Derek Holt
  • 98.2k
2 votes
1 answer
98 views

What are the angles of this amazing triangle?

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mathperson314
  • 4,964
4 votes
1 answer
181 views

Is there a converse of the Copeland-Erdős theorem on normal numbers?

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Jotazuma
  • 162
0 votes
1 answer
98 views

Formula for the number of divisors of an integer

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Dietrich Burde
  • 143k
0 votes
0 answers
54 views

Check proof that the determinant of a polynomial matrix commute with evaluation

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Agustin G.
  • 427
1 vote
1 answer
160 views

Min $S$ satisfying $\frac{a}{S-a}\frac{b}{S-b}\frac{c}{S-c}=\frac{1}{60}$ and some constraints

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Glory2Ukraine
  • 208
2 votes
3 answers
461 views

Proof that $\mathbb{Q}[\sqrt{-6}]$ has class number 2

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KCd
  • 57k
3 votes
2 answers
925 views

Find Area of 3 Sector Circle, Variable center point

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user1711873
  • 86
10 votes
4 answers
1k views

Why Is the Dual Basis Mathematically Unavoidable?

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Nicolas Malebranche
  • 111
1 vote
0 answers
31 views

Is there a way to rewrite a differential equation to obtain uniqueness? Lipschitz

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Diana Pestana
  • 1,662
2 votes
3 answers
1k views

What does wedge or caret mean in a matrix context?

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M Marques
  • 1
49 votes
2 answers
11k views

The significance and acceptance of Helfgott’s proof of the weak Goldbach Conjecture

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H A Helfgott
  • 1,997
0 votes
0 answers
25 views

When does an optimization problem that is "worth solving" also satisfy strong duality?

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Your neighbor Todorovich
  • 8,703
1 vote
2 answers
780 views

Expected value over many trials

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johnnyb
  • 3,782
5 votes
1 answer
291 views

Integral evaluation

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Dhairya Kumar
  • 89
12 votes
2 answers
1k views

Is the transfer principle useless?

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Henry
  • 721
4 votes
0 answers
67 views

Homeomorphic smooth Vector bundle that aren't diffeomorphic

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Manuel Bonanno
  • 705
5 votes
3 answers
166 views

Hint to solve geometry question with angle bisector

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dfnu
  • 8,378
0 votes
1 answer
53 views

Closure of series using prime factorization

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Tveltzel
  • 642
2 votes
2 answers
257 views

How to show a functional has infinitely many minimizers?

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Rodrigo de Azevedo
  • 23.6k
3 votes
3 answers
140 views

The only area–preserving linear symmetry of a strictly convex body fixing a boundary point is the identity?

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daw
  • 55.6k
3 votes
1 answer
62 views

Expectation of an absolute value

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Eric_
  • 1,029
2 votes
1 answer
53 views

Set-theoretical conventions in Pedersen's Analysis Now

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Carl Mummert
  • 86.7k
1 vote
3 answers
2k views

Method to multiply many matrices simultaneously

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Rodrigo de Azevedo
  • 23.6k
7 votes
4 answers
482 views

Indefinite integral $\int\frac{1}{\sqrt{1-\text{csch}^2 x}}\,dx$

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Integreek
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0 answers
22 views

The Gateaux derivative and the Jacobian

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Jared
  • 255
23 votes
5 answers
7k views

Is $0$ an imaginary number?

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Alexey
  • 2,786
11 votes
6 answers
888 views

What is the easiest way to integrate $\left(\frac{1-x}{1+x}\right)^{1/2}?$

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Integreek
  • 8,973
3 votes
1 answer
73 views

Closed form for a symmetric sum of squared binomials

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pioo
  • 553
4 votes
4 answers
303 views
+50

What sets of digits can be used to represent all of the real numbers in a ternary numeral system?

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Daniel Smania
  • 8,767
-1 votes
0 answers
77 views

Determine the convergence behavior of $\sum_{n=1}^{\infty} \frac{a_{n}}{n^x}$

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user3835
  • 141
2 votes
2 answers
93 views

Prove that $\sum_{k=1}^{n} \left\lfloor \log_{2}\!\left(\frac{2n}{2k-1}\right) \right\rfloor = n$ where $n$ is a natural number.

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Anshul Prajapati
  • 35
0 votes
1 answer
44 views

Is the complement of the closure of $x^{n_1} + y^{n_2} = z^{n_3}$ for all positive integers $n_i$ given by these two regions?

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Christophe Boilley
  • 12.4k
3 votes
1 answer
723 views

Retract of a CW-complex

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Alexis
  • 111
0 votes
0 answers
40 views

Modelling a dice game without straightforward computation

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Jack Meow Meow
  • 359
0 votes
1 answer
769 views

Obtain (or close to) Identity matrix by multiplying two vectors such as: $D * (C)^H = I$

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CommunityBot
  • 1
1 vote
1 answer
88 views

Analytic sum of an alternating series involving $n/(n+\sqrt{a^2+n^2})^2$

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PierreCarre
  • 24k
2 votes
3 answers
864 views

Showing $x^4+x^2+x+1$ irreducible over $\mathbb{Z_3}$

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Jianing Song
  • 2,781
2 votes
1 answer
777 views

Absolute value of derivative of complex analytic function

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CommunityBot
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1 vote
0 answers
41 views

Most general Logarithm of a matrix

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lambda
  • 11
0 votes
0 answers
26 views

Ideal of maximal minors is radical when rank never drops by more than 1 [Reference request]

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Leobeth
  • 2,868
3 votes
1 answer
151 views
+50

For which real $\beta$ there exist concave(convex upwards) functions $f, g: (0;1) \to (0;+\infty)$ such that $\frac{f(x)}{g(x)}=(1+x)^\beta$?

pioo's user avatar
pioo
  • 553
13 votes
3 answers
2k views

What is $\mathbb{C}^{\mathrm{Aut}(\mathbb{C}/\mathbb{Q})}$?

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Martin Sleziak
  • 56.4k
0 votes
0 answers
26 views

Study of non linear dynamical system

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thibault_student
  • 245
65 votes
2 answers
4k views

When are nonintersecting finite degree field extensions linearly disjoint?

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Martin Sleziak
  • 56.4k
0 votes
1 answer
2k views

Markov chain having unique stationary distribution

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0 votes
1 answer
50 views

A question concerning the duality bracket of $W^{-1,p'}(\Omega)$ with $W_0^{1,p}(\Omega)$ relevant to $L^2(\Omega)$ inner product

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daw
  • 55.6k
1 vote
0 answers
40 views

Why doesn't Montel's Theorem imply the space of analytic functions is locally compact?

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user760
  • 2,900
0 votes
2 answers
124 views

Evaluate (when possible) $\sum_{n=0}^{+\infty}\ln\left(2\cos\frac{\alpha}{2^n}-1\right)$

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zaknenou
  • 197
0 votes
0 answers
34 views

The nature of elements in local rings and local parameters

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zyy
  • 1,229
1 vote
0 answers
42 views

Asymptotic Variance

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SATYA
  • 87
2 votes
1 answer
37 views

Upper-bounded version of the Gale-Ryser theorem

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Sacha Bernheim
  • 26
2 votes
1 answer
51 views

Counterexample request: $\sigma$-algebra with no smallest set containing a given (non-measurable) set?

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Michael Greinecker
  • 35.4k
1 vote
0 answers
29 views

Prob. 7, Sec. 30, in Munkres' TOPOLOGY, 2nd ed: Is $\overline{S_\Omega}$ first-countable? second-countable? separable? Lindelof?

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Saaqib Mahmood
  • 27.8k
38 votes
7 answers
33k views

If $n\ne 4$ is composite, then $n$ divides $(n-1)!$.

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bhache
  • 37
1 vote
1 answer
84 views

Restricted Euler function

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Greg Martin
  • 94.2k
7 votes
3 answers
271 views

Telescopic series: how to identify it after breaking it down into partial fractions?

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RobPratt
  • 52.3k
0 votes
0 answers
34 views

Cohomology classes on manifolds induce homology and bordism classes of Eilenberg-MacLane spaces

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tl981862
  • 43
12 votes
3 answers
2k views

$\int_{0}^{\pi/2}\arctan(\sin(x))dx=\frac{\pi^2}{8}-\frac{\ln^2(\sqrt{2}-1)}{2}$

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Quanto
  • 124k
0 votes
1 answer
62 views

Where does this partition-of-unity argument not work in general?

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Paul Frost
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