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Interesting 55 Bountied Hot Week Month
3 votes
1 answer
25 views

$0 \leqslant a \leqslant b \Rightarrow \|a\| \leqslant \|b\|$ in a $C^*$-algebra

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Robert Furber
  • 1,098
3 votes
1 answer
59 views

Are there more real numbers in the interval $[1,\infty)$ than in the interval $(0,1]$? Or not?

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Dan
  • 7,196
1 vote
3 answers
37 views

For what values of $p>0$ is $\lim_{n\rightarrow\infty}\int_0^n\frac{(1-\frac{x}{n})^ne^x}{n^p}=0$?

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Claude Leibovici
  • 213k
0 votes
0 answers
2 views

Abstract integral interpretation

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CBBAM
  • 1,202
2 votes
1 answer
3k views

Find the potential function of a conservative vector field

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CommunityBot
  • 1
1 vote
0 answers
4 views

Dependency of the value of this Integral on the path taken.

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Vaibhav C M
  • 27
2 votes
1 answer
38 views

Is there a function $f$ from reals to reals such that every non-vertical line intersects $f$ infinitely many times?

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marty cohen
  • 101k
1 vote
0 answers
6 views

Show that $f(x)=x^2+\frac{a}{x}$ cannot have a local maximum for any value of $a$.

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Souparna Pal
  • 26
2 votes
0 answers
21 views

Given matrix associated to linear transformation find the basis it corresponds to

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Peter Sampodiras
  • 21
1 vote
0 answers
19 views

Exercise on continuous functions, analysis 1

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Brandon Araya
  • 11
4 votes
3 answers
52 views

If $ax^2 + 2hxy + by^2 = 0$ (here $a, b, h$ are real constants), then find $\frac{dy}{dx}$.

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Yooo
  • 1,721
3 votes
2 answers
18 views

In definition of a topology, is including the empty set and the set itself redundant?

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Eevee Trainer
  • 29.5k
1 vote
1 answer
19 views

Number of functions under some conditions

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Yathiraj Sharma
  • 781
2 votes
0 answers
25 views

Sum of Zero Nim-sum k-tuple Revisited

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Hang Wu
  • 1,466
2 votes
1 answer
13 views

Direct sum of small modules is small, also direct summands of small modules are small.

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azif00
  • 17.2k
2 votes
2 answers
16 views

Maximality of matching after contracting an odd cycle in a graph

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Math_Day
  • 1,153
1 vote
0 answers
5 views

Expand [a+b*log(1-x)]^{-1} as power seires in x

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user55777
  • 157
1 vote
1 answer
8 views

Evaluate/asymptotic of the sum $\sum_{a = 1}^{L \left({N}\right)} \left({- 1}\right)^{\left\lfloor{N/\left({2\, a + 1}\right)}\right\rfloor}$

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marty cohen
  • 101k
2 votes
0 answers
18k views

3-digit chopping vs 3-digit rounding and relative error

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ice1000
  • 173
1 vote
0 answers
7 views

Geometric Interpretation of Jacobson rings -- Every locally closed subsets of $\mathrm{Spec} A$ consists of a single point is closed

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Hetong Xu
  • 1,387
3 votes
1 answer
61 views

Find the derivative of $\frac{d}{dx}\left(\tan \left(\sqrt{x}\right)\right)$ - no chain rule

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Dan
  • 7,196
3 votes
1 answer
53 views

A positive semidefinite bilinear form must be degenerate?

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Maaour
  • 329
1 vote
0 answers
7 views

Limiting probability measure on an increasing sequence of finite products

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caffeinemachine
  • 16.7k
2 votes
0 answers
50 views

Proof from Lang’s Basic Mathematics

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Mor A.
  • 621
0 votes
0 answers
19 views

consider the following relation on the set of positive integers.

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user264745
  • 1,381
2 votes
1 answer
41 views

Meaning of $\big|_{t=0}$ beside a derivative in a theorem about the properties of the characteristic function of a random variable.

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Galen
  • 1,306
6 votes
1 answer
31 views

The coupon collector's most collected coupon

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Sangchul Lee
  • 140k
0 votes
0 answers
15 views

What are the conditions for cosets of a certain group to form a group themselves?

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Sammy Black
  • 16.8k
0 votes
0 answers
5 views

This is Stein fourier analysis. In section 3.3，I really don't understand how he gets to the final result(equation (4)),can someone explain in detail?

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cyz20030307
  • 1
3 votes
1 answer
82 views

Find a polynomial of the form $F(x,y,z)$ of degree $3$ such that $F(a,b,c) = 0 \pmod{5}$ iff $a,b,c= 0 \pmod{5}$

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Mike
  • 15.5k
0 votes
0 answers
19 views

Second inner product.

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finn32497
  • 21
1 vote
1 answer
13 views

Properties of conformal maps

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Binxu Wang 王彬旭
  • 989
-1 votes
0 answers
8 views

Are there any theorems about the restriction of a partial order?

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Ypbor
  • 165
1 vote
0 answers
10 views

definition of closed immersions of schemes

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Adam
  • 267
1 vote
2 answers
9 views

Must a certain continuous map have 0 in its image, given that its restriction to the unit sphere is homotopic to the identity?

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Ruy
  • 13.6k
0 votes
0 answers
8 views

Find a process $\left(A_{n}\right)_{n}$ such that $\left(\sum^{n} X_{i}\right)^{2}-A_{n}$ is a martingale.

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Stochastichelp
  • 175
0 votes
1 answer
22 views

$u$ be the sol of $\Delta u+ a_i(x)\frac{\partial u}{\partial x_i}= f(x)$ if $f\geq 0$ then u is constant and $f=0$

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JackT
  • 3,496
2 votes
2 answers
1k views

Semi-Infinite String equation

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CommunityBot
  • 1
0 votes
3 answers
33 views

Let $A\in\mathbb{R}^{2\times 2}$ be such that $\det(A)=d\ne0$ and $\det(A+d\cdot\text{Adj}(A))=0$. Evaluate $\det(A-d\cdot\text{Adj}(A))$.

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Sourav Ghosh
  • 4,014
0 votes
1 answer
15 views

Origin of a term in an inequality.

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M. Logic
  • 1,175
1 vote
0 answers
8 views

Elliptic regularity with right-hand side in $H^{-1/2}$

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Numa
  • 73
0 votes
0 answers
10 views

When we calculate the irr, how to decide the initial range of irr?

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Paul
  • 1
0 votes
1 answer
10 views

Almost Sure Convergence of a Random Variable

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Jason
  • 15k
0 votes
0 answers
18 views

Why is "More Data Better than Less Data"?

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stats_noob
  • 1,702
1 vote
0 answers
13 views

Elementarily equivalent models of arithmetic that are not isomorphic.

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ngc1300
  • 493
0 votes
1 answer
22 views

Function class consisting of gradients of real-valued convex functions

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max_zorn
  • 4,477
0 votes
0 answers
22 views

What is the difference between the principal square root of $x$ and $x^{1/2}$?

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unloadedmaterial
  • 1
0 votes
0 answers
6 views

Conditional distribution of one of the two exponential random variables, given one is smaller than the other

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Tony B
  • 1,922
0 votes
1 answer
22 views

Pullback is not exact

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Hank Scorpio
  • 2,159
1 vote
0 answers
6 views

Are we able to Compare the Fisher Information of Two Variables?

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stats_noob
  • 1,702
0 votes
0 answers
9 views

can we always get the variables of a system of linear equations given the system is valid?

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A Farmanbar
  • 115
3 votes
0 answers
29 views

Calculation on Riemannian manifolds

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kid111
  • 369
1 vote
0 answers
55 views

Prove that if $y \neq 0$ and $n$ is odd, then $x^n+y^n=(x+y)^n$ only if $x=0$ or $x=-y$ (Spivak's Calculus, Ch. 11)

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evianpring
  • 1,655
0 votes
0 answers
11 views

Homology of the complement of a simple closed curve in a surface

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stupid_question_bot
  • 643
0 votes
0 answers
15 views

Cardinal of a set (proof verification)

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Celine Harumi
  • 2,347
4 votes
1 answer
99 views

Why this partial function is not computable?

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Mitchell Spector
  • 8,561
0 votes
0 answers
23 views

I cannot prove that $T$ is diagonalizable $\Rightarrow$ $T|_{V_1},T|_{V_2},\dots,T|_{V_r}$ are diagonalizable.

user avatar
tchappy ha
  • 6,081
2 votes
0 answers
29 views

An interesting recurrent equality, possibly easier to solve in its differential form?

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Nen
  • 455
6 votes
1 answer
3k views

Bayesian Interpretation for Ridge Regression and the Lasso

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CommunityBot
  • 1
0 votes
1 answer
22 views

How to linearize a state space equation with higher order $>2$?

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RobPratt
  • 33k
0 votes
0 answers
16 views

For a compactly supported, continuously differentiable function $f$, do we have $\frac{f(x+h)-f(x)}{h}\to f'(x)$ uniformly?

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jk001
  • 717
2 votes
0 answers
21 views

"Spanning" of solutions of ordinary differential equations

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Alp Uzman
  • 6,864
2 votes
0 answers
37 views

Help showing that two sets are equal.

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Logi
  • 485
1 vote
0 answers
21 views

Why does the following remark on probability space not work on infinite, yet countable, sets?

user avatar
DomM
  • 11
2 votes
1 answer
21 views

Proof of Wronskian relation using induction

user avatar
Binxu Wang 王彬旭
  • 989
1 vote
1 answer
41 views

The derivative of a semialgebraic map is semialgebraic

user avatar
KReiser
  • 49.7k
6 votes
0 answers
53 views

Why does Galois theory most naturally take place in the context of fields?

user avatar
D.R.
  • 5,674
3 votes
1 answer
38 views

On the number of roots of $p(z,\bar z)$

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dxiv
  • 68.4k
5 votes
4 answers
150 views

Inequality involving sums with binomial coefficient

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River Li
  • 22.5k
2 votes
2 answers
72 views

What does it mean to lift a curve $\gamma$ in $\mathbb{C}\mathbb{P}^n$?

user avatar
mike
  • 464
3 votes
1 answer
25 views

What do the elements of the chains of a simplicial complex represent?

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Sammy Black
  • 16.8k
1 vote
0 answers
21 views

Global Langlands for tori?

user avatar
Tian An
  • 777
1 vote
1 answer
13 views

Conditioning in Event Language VS Proposition Language

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Graham Kemp
  • 119k
2 votes
0 answers
32 views

Why is $\int_{0}^{2\pi} \int_0^{2\pi} \frac{\ln(21-4(\cos x+\cos y+\cos(x+y)))}{2\ln(9/2)}\frac{dx}{2\pi} \frac{dy}{2\pi}$ almost $1$?

user avatar
Blue
  • 69.2k
1 vote
1 answer
29 views

An inequality: from the complex to the real case.

user avatar
Kavi Rama Murthy
  • 301k
3 votes
0 answers
33 views

What' s the asymptotic behaviour of this integral?

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Gary
  • 19.7k
1 vote
0 answers
25 views

Determine if $f(x,y)=e^{-xy}\cos(2x)\cos(y)$ is integrable via Fubini

user avatar
Gary
  • 19.7k
2 votes
0 answers
21 views

Calculating the angle between 2 one-sided surfaces.

user avatar
vaana
  • 21
2 votes
2 answers
78 views

Are $\frac{p^2+1}{2}$ and $\frac{p^{5n}(p^5-1)}{2}$ are coprime to each other, $n \in \mathbb{N}$?

user avatar
ewong
  • 239
1 vote
0 answers
14 views

Exemple where tower property of conditional expectation is NOT verify

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X0-user-0X
  • 53
1 vote
0 answers
15 views

Approximating an open set in measure with another open set whose boundary has zero measure

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Nick Sun
  • 31
1 vote
0 answers
21 views

Quadratic Reciprocity as an Analytic Statement

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modperspec
  • 635
9 votes
0 answers
103 views

Collatz conjecture but with $n^2-1$ instead of $3n+1.$ Does the sequence starting with $13$ go to infinity?

user avatar
lulu
  • 62.6k
1 vote
0 answers
27 views

Proof: $C^\infty[0,1]$ is dense in $L^2[0,1]$

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X0-user-0X
  • 53
0 votes
0 answers
9 views

What set of matrices $X,Y$ satisfy $X \circ Y = X P Y$ for at least one permutation matrix $P$?

user avatar
Galen
  • 1,306
3 votes
1 answer
25 views

Are invertibly cobordant manifolds diffeomorphic

user avatar
kamills
  • 1,696
0 votes
0 answers
10 views

Find $\mathbb{E}[\hat{\alpha}]$. Suggest a new estimate $\check{\alpha}$ of $\alpha$ which is unbiased, such that $\mathbb{E}[\check{\alpha}]=a$

user avatar
Mugge
  • 1
1 vote
0 answers
15 views

General form of rank $2$ tensor invaiant under certain rotations

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ContraKinta
  • 677
0 votes
0 answers
17 views

Goldbach Conjecture and Triangular Number

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MD SHAHIDUL ISLAM
  • 1
0 votes
2 answers
56 views

Solution of $\theta$ when $\tan(\theta)-\sin(\theta)=\frac{\sqrt3}{2}$

user avatar
Somos
  • 29.1k
2 votes
0 answers
13 views

Can we calculate the opponent's hidden values in this statistical battle?

user avatar
Avestura
  • 129
0 votes
2 answers
1k views

Probability of being selected in a raffle

user avatar
CommunityBot
  • 1
3 votes
1 answer
97 views

Prob. 10, Sec. 30, in Munkres' TOPOLOGY, 2nd ed: A countable product of separable spaces is also separable

user avatar
Saaqib Mahmood
  • 23.7k
1 vote
0 answers
9 views

Decomposing a big and nef divisor into ample + effective

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Bun
  • 93
3 votes
0 answers
9 views

Divisibility of unitriangular matrices over a field of characteristic 0

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square17
  • 123
0 votes
0 answers
42 views

How to know what to study based on past examinations?

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algevristis
  • 507
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