Mathematics Stack Exchange

8

votes

1

answer

121

views

Solving quintic equations of the form $x^5-x+A=0$

polynomials quintic-equations

modified 2 mins ago Elliot Yu 274

0

votes

1

answer

16

views

Solution to integral $\int_0^\infty F(x)~x~\mathrm{d}x$ for any CDF $F(x)$?

integration probability-distributions definite-integrals normal-distribution expected-value

answered 1 min ago okan erturk 19

-1

votes

1

answer

14

views

Let $(a_k)$ be a sequence s.t. $a_k>0$. If $\lim_{k\to \infty} k^2a_k = 1$, the series $\sum_{k=1}^\infty a_k$ converges

real-analysis calculus sequences-and-series general-topology limits

answered 1 min ago zkutch 3,835

-1

votes

1

answer

23

views

+50

If $\min_x \max_y: f(x,y)$ is convex and concave saddle point problem, is this correct $\min_x \max_y: f(x,y) = \max_x \min_y: -f(x,y)$?

optimization game-theory

answered 4 mins ago DanielHarlow 111

5

votes

1

answer

58

views

Verifying a proof that $\frac{x^2}{y^3}+\frac{y^2}{z^3}+\frac{z^2}{x^3}≥x^2+y^2+z^2$ when $xyz=1$ and x,y,z are positive real number

inequality summation a.m.-g.m.-inequality

modified 4 mins ago Michael Rozenberg 161k

0

votes

0

answers

11

views

closed ball with topological boundary

general-topology

modified 5 mins ago yi_li 475

2

votes

2

answers

39

views

Linear operators well-defined by matrices in $l^2$ are bounded

matrices functional-analysis

modified 7 mins ago Bart Michels 21.7k

0

votes

0

answers

39

views

Is $\infty < (\infty +2)$ true?

infinity

modified 7 mins ago J. W. Tanner 42.5k

2

votes

1

answer

55

views

Limit of ${ \lim_{(x,y)\to(0,0)} {(\left| x \right| + \left| y \right|) \ln{(x^2 + y^4)} }}$

limits multivariable-calculus

answered 8 mins ago enzotib 7,153

0

votes

0

answers

8

views

Integration, confluent hypergeometric functions

integration definite-integrals hypergeometric-function

modified 8 mins ago Priyadarshi Mukherjee 37

0

votes

2

answers

15

views

Double integral over a specific non-linear region

integration multivariable-calculus

modified 8 mins ago zkutch 3,835

1

vote

1

answer

27

views

Show that $\sum\frac{(-1)^{n+1}} {{n}^r} \sum\frac{(-1)^{n+1}} {{n}^s} $ by Abel's rule forms a series that doesn't converge when r+s=1.

complex-analysis absolute-convergence

modified 9 mins ago Charlie Chang 919

1

vote

1

answer

54

views

+100

An argument in approximating Riemann-type sums: assuming without loss of generality a given partition is contained in all partitions.

real-analysis analysis probability-theory measure-theory riemann-sum

answered 13 mins ago postmortes 4,812

5

votes

1

answer

75

views

Given $\triangle ABC$ can we construct point $O$ such that $AO\times BC=BO\times AC=CO\times AB$?

geometry euclidean-geometry plane-geometry geometric-construction

modified 13 mins ago Oscar Lanzi 19.9k

0

votes

0

answers

6

views

Projection on Tensor Product of Hilbert Space (The symmetric subproduct system SSPH).

functional-analysis hilbert-spaces tensor-products orthonormal projection

asked 14 mins ago Naseem H Baransi 5

0

votes

1

answer

14

views

Density and finding points with a defined property

real-analysis general-topology analysis metric-spaces

answered 15 mins ago alphaomega 1,334

0

votes

1

answer

17

views

Multiplying cycles

group-theory permutations permutation-cycles

answered 16 mins ago Arthur 164k

2

votes

1

answer

42

views

Additive function differentiable at 0

functions

modified 17 mins ago Tortar 696

0

votes

1

answer

26

views

Find the direction of curve at the point $(0,0)$

calculus

modified 19 mins ago Integrand 6,159

1

vote

0

answers

11

views

Computing the determinant of a Vandermonde-like matrix

matrices polynomials determinant

modified 23 mins ago A.P. 9,103

0

votes

0

answers

33

views

Unknown triangle property of constant $( ab+bc+ca )/\Delta = Q_2$

euclidean-geometry triangles locus

modified 23 mins ago Narasimham 28.6k

0

votes

0

answers

10

views

Finding expression for expected downtime of Gamma process

stochastic-processes gamma-distribution

modified 24 mins ago Rel_Ai 1

1

vote

0

answers

11

views

References about continuity and differentiability in two and three dimensional

calculus multivariable-calculus reference-request

modified 24 mins ago J. W. Tanner 42.5k

1

vote

0

answers

9

views

Maximum Likelihood Estimation and Moment Estimator

expected-value density-function

modified 26 mins ago handy 143

0

votes

0

answers

4

views

The asymptotic properties of estimators conditional on a fixed estimator

calculus statistics taylor-expansion statistical-inference maximum-likelihood

asked 27 mins ago Churchill 1

0

votes

1

answer

26

views

Why is the solution to the differential equation $v'(t)=\Lambda v,$ $ v(t)=\exp(\Lambda t)v(0)$

ordinary-differential-equations

answered 27 mins ago mjw 3,715

9

votes

0

answers

207

views

Optimal Compass and Straightedge Constructions

geometry optimization euclidean-geometry computational-complexity geometric-construction

modified 33 mins ago nbubis 30.4k

0

votes

1

answer

30

views

mollification of harmonic function is harmonic (Green's identity)

multivariable-calculus partial-differential-equations greens-theorem

modified 33 mins ago SC2020 83

0

votes

1

answer

17

views

Nested probability

probability

answered 55 secs ago Ekin 66

0

votes

0

answers

12

views

Notation for family of linear maps that are bounded uniformly?

functional-analysis reference-request notation banach-spaces

asked 34 mins ago StopUsingFacebook 626

0

votes

1

answer

19

views

Would this method find the non-shortest induced path in a graph $G$ in $O(n^2\ln n)$?

graph-theory algorithms

answered 35 mins ago Ekin 66

1

vote

0

answers

9

views

Tangent and normal of point function

vector-analysis vector-fields

modified 40 mins ago Arthur 164k

0

votes

0

answers

16

views

i have confusion in the answer given in book

permutations symmetric-matrices

asked 40 mins ago Swapnil 1

2

votes

1

answer

22

views

Understanding Arithmetic Progression in $[N]$ vs. $\mathbb{Z}_N$

combinatorics number-theory arithmetic-progressions additive-combinatorics

answered 42 mins ago Thomas Bloom 1,298

1

vote

0

answers

8

views

Let $B_f$ be the braid group on $f$ strings, and let $\phi:B_f \rightarrow End(V)$ be a representation…

abstract-algebra representation-theory

modified 42 mins ago GageMartin 103

0

votes

1

answer

27

views

Differential equation solution using Method of undetermined coefficients.

ordinary-differential-equations

modified 46 mins ago Aryadeva 24.6k

2

votes

1

answer

38

views

Linearizing a 2nd order ODE

real-analysis ordinary-differential-equations

answered 49 mins ago Lutz Lehmann 85.9k

3

votes

1

answer

790

views

Sobolev multiplication theorem

sobolev-spaces

modified 51 mins ago Community♦ 1

2

votes

0

answers

114

views

Why is the Lebesgue Measure over $[0,1]$ equal to the Probability measure over $[0,1]$?

probability-theory measure-theory lebesgue-measure outer-measure

modified 55 mins ago Arbuja 186

1

vote

2

answers

45

views

Which inequality is $\frac {-3x-15}{2} \lt 0$ equivalent to?

inequality

modified 57 mins ago Subhajit 1,311

2

votes

0

answers

21

views

Change of variables in a Taylor's polynomial

calculus taylor-expansion

asked 58 mins ago user266148 33

2

votes

0

answers

39

views

+50

Determine the set of values taken by a Bohr's function

functions graphing-functions analytic-number-theory dirichlet-series

modified 59 mins ago Yourong 'DZR' Zang 1,080

3

votes

1

answer

47

views

Tangent bundle of the incidence variety and its Chern class

algebraic-geometry algebraic-topology intersection-theory k-theory topological-k-theory

answered 59 mins ago Teddyboer 494

2

votes

1

answer

9

views

Expansion of an exponential into a linear series

sequences-and-series taylor-expansion

answered 1 hour ago Vercassivelaunos 1,852

2

votes

0

answers

10

views

What is the distribution of the conditional probability $(N(a)|N(b) =c )$ of a poisson process $N(t)\geq t$ if $a>b$

probability probability-distributions poisson-process

asked 1 hour ago rogger k9 53

1

vote

0

answers

9

views

Generalized (Gnedenko Kolmogorov) limit theorem for distribution with inverse cube law

probability probability-theory probability-distributions

asked 1 hour ago Étienne Bézout 1,542

1

vote

0

answers

7

views

Let $R$ be a commutative ring with unity and $f:R \to R$ be a ring homomorphism. If $S = \{a \in R | f(a)=a \}$, show that $S$ is subring of $R$.

ring-theory ring-homomorphism

asked 1 hour ago user795084 193

1

vote

0

answers

12

views

A question about intersection of two cones in $\mathbb{R}^{n\times n}$

linear-algebra linear-programming convex-geometry

asked 1 hour ago User_09 11

1

vote

0

answers

35

views

How to mathematically express a state from object properties

systems-of-equations

modified 1 hour ago trshmanx 21

2

votes

1

answer

22

views

When u-substituted, what does the transformed integral represent?

calculus integration definite-integrals

modified 1 hour ago crush3dice 43

1

vote

0

answers

7

views

Is there a bijective correspondence between metric tensors and coordinate systems?

metric-spaces coordinate-systems tensors

asked 1 hour ago Fausto Vezzaro 411

1

vote

1

answer

31

views

Examples for completions of number fields

abstract-algebra number-theory extension-field cauchy-sequences local-field

modified 1 hour ago tomasz 28.3k

1

vote

0

answers

16

views

2 parametrizations can be linked by a deffeomorphism

geometry differential-geometry

modified 1 hour ago briantylf 472

0

votes

1

answer

21

views

Probability of selecting the index corresponding to the higher parameter looking at frequencies of independent Bernoulli processes.

probability statistics probability-distributions stochastic-processes probability-limit-theorems

modified 1 hour ago Bob 3,666

2

votes

1

answer

19

views

Poisson process into a series of Bernouilli trial problem

probability probability-distributions poisson-process

answered 1 min ago G Cab 27.3k

1

vote

0

answers

12

views

poisson process extended into another joint distribution

probability probability-distributions poisson-process

modified 1 hour ago clover k 63

3

votes

0

answers

19

views

An ascending union of FATR groups is FATR

abstract-algebra group-theory solvable-groups

asked 1 hour ago Mariah 3,624

3

votes

0

answers

37

views

Abel's summation formula and approximating an integral of Jacobi theta functions

sequences-and-series approximation theta-functions

modified 1 hour ago SaMaSo 196

2

votes

2

answers

25

views

proving multiplicative property of Euler's totient function

abstract-algebra number-theory modular-arithmetic

answered 1 hour ago Bernard 153k

2

votes

1

answer

47

views

variation of Vitali in $\mathbb{R}^2$

real-analysis measure-theory covering-spaces

answered 1 hour ago Samantha Wyler 586

1

vote

0

answers

9

views

Doubt in proof of naive (epsilon,delta) PAC algorithm for multi armed bandits

probability-theory proof-explanation machine-learning

asked 1 hour ago kronkman 11

1

vote

0

answers

15

views

Let $A$ be the diagonal operator on $\mathcal H$ given by $Ae_n=\lambda_n e_n$, where $\sup_n|\lambda_n|<\infty. $ what is $\{A\}'$

functional-analysis operator-theory hilbert-spaces

asked 1 hour ago user62498 2,998

5

votes

4

answers

72

views

Find all values of $a$ for which the maximum value of $f(x)=\frac{ax-1}{x^4-x^2+1}$equals $1$.

calculus algebra-precalculus derivatives maxima-minima

modified 1 hour ago VIVID 3,190

1

vote

1

answer

16

views

Is there a relation in geometry in which the third power of a segment is a function of other segments of a triangle?

analytic-geometry

answered 1 hour ago David C. Ullrich 75.8k

1

vote

0

answers

8

views

Looking for original reference/derivation for expansion of $J_0\left(z\sin\alpha\right)$ in terms of squared Bessel functions and cosines

reference-request bessel-functions

asked 1 hour ago schade96 11

0

votes

1

answer

22

views

How many strings of eight English letters are there that contain at least one vowel, if letters can be repeated?

combinatorics

answered 1 hour ago Henno Brandsma 172k

0

votes

0

answers

26

views

Convolving a relatively simple function $n$ times.

real-analysis integration convolution

modified 1 hour ago Bernard 153k

0

votes

1

answer

12

views

Method of moments - lognormal distribution

statistics

answered 1 hour ago Clarinetist 14.7k

10

votes

0

answers

625

views

In Search Of Elementary Proof Of Kobayashi's Theorem

number-theory elementary-number-theory prime-numbers diophantine-approximation geometry-of-numbers

modified 1 hour ago Shubhrajit Bhattacharya 3,648

1

vote

0

answers

32

views

What do “soundness” and “completeness” mean?

logic formal-proofs

asked 1 hour ago Tim 35.3k

0

votes

0

answers

20

views

Linear model for vehicle kinematics

optimization mathematical-modeling differential kinematics

modified 1 hour ago John B 14.1k

1

vote

0

answers

32

views

Defining multiplication on the non-negative hyperreal numbers ala the Tarski/Eudoxus technique

logic soft-question axioms second-order-logic

modified 1 hour ago Andrés E. Caicedo 71.2k

5

votes

1

answer

215

views

Lagrange interpolation of multivariate polynomials

multivariable-calculus polynomials lagrange-interpolation

modified 1 hour ago sera 1,972

0

votes

0

answers

14

views

Jacobson Lemma from Herstein

linear-algebra matrices linear-transformations

modified 1 hour ago Tanya Rastogi 39

3

votes

1

answer

36

views

A sequence of curves $(x_n)$ for which $g(\dot{x}_n, \dot{x}_n)$ is uniformly bounded converges weakly in $H^1([0, 1], M)$

functional-analysis hilbert-spaces riemannian-geometry sobolev-spaces weak-convergence

answered 2 hours ago s.harp 15.5k

0

votes

0

answers

31

views

Distribution space is a Frechet or Sequential space?

sobolev-spaces distribution-theory topological-vector-spaces locally-convex-spaces

modified 2 hours ago Christian 535

4

votes

0

answers

17

views

Transforming a disk to a ring

geometric-transformation

modified 2 hours ago lhf 192k

0

votes

0

answers

17

views

D'Alembert's formula with initial conditions hidden

partial-differential-equations wave-equation initial-value-problems

modified 2 hours ago Lanzs 1

1

vote

0

answers

9

views

Linearize product of Two Special Ordered Sets and minimize number of variables

optimization nonlinear-optimization linearization

asked 2 hours ago Kamer73 11

2

votes

0

answers

23

views

Zero sets of sections of vector bundles

reference-request algebraic-topology homology-cohomology vector-bundles characteristic-classes

asked 2 hours ago Teddyboer 494

0

votes

0

answers

16

views

Logarithmic convexity of Sobolev norms

functional-analysis partial-differential-equations sobolev-spaces

modified 2 hours ago curious george 26

0

votes

0

answers

10

views

Relationship between fiber volume form on the sphere bundle and connection forms on the frame bundle

riemannian-geometry differential-forms connections

modified 2 hours ago Thorgott 2,716

0

votes

0

answers

10

views

Question related to sum of digits and formula for $f_n^m(y)$

combinatorics elementary-number-theory decimal-expansion

modified 2 hours ago Pruthviraj 2,117

0

votes

0

answers

27

views

Adjoint mapping for matrices

linear-algebra matrices adjoint-operators automorphism-group hermitian-matrices

modified 2 hours ago Tanya Rastogi 39

1

vote

0

answers

21

views

How to solve this Fourier integral?

fourier-analysis self-learning fourier-transform cauchy-problem

asked 2 hours ago NathanaelFisher 11

0

votes

0

answers

11

views

Help deriving a Fourier-Galerkin approximation for a variable coefficient partial differential equation

partial-differential-equations spectral-theory galerkin-methods

modified 2 hours ago mattos 3,264

0

votes

0

answers

17

views

Variant of parabolic maximum principle: $\partial_t u\ge \Delta_x u + b\cdot\nabla_x u-u \;\Rightarrow\; u\ge e^{-t}\inf_y u(0,y)$

partial-differential-equations reference-request maximum-principle parabolic-pde

modified 2 hours ago Mars Plastic 3,639

0

votes

0

answers

18

views

Compute the area of a hypersurface with a Dirac delta.

geometry multivariable-calculus dirac-delta

asked 2 hours ago Elena Kogan 21

0

votes

0

answers

10

views

Continuous stochastic process and symmetric differences.

probability-theory measure-theory stochastic-processes stochastic-calculus

modified 2 hours ago cts12 35

0

votes

1

answer

86

views

finding the integral of:$\int_0^\infty \frac{1}{(1+x^2)^n}$ for $n<1$

calculus integration

modified 2 hours ago EDX 1,025

0

votes

0

answers

9

views

Proving $S(A:B)+S(A:C) \le 2S(A)$ using subadditivity

information-theory entropy quantum-information

asked 3 hours ago GaussStrife 13

4

votes

1

answer

167

views

+100

Control system problem

linear-algebra optimization control-theory linear-control

modified 3 hours ago Novice 383

0

votes

2

answers

34

views

Continuous function from $\mathbb{R}$ standard topology to $\mathbb{R}_l$ lower limit topology

general-topology continuity sorgenfrey-line

modified 3 hours ago Martin Sleziak 51.4k

4

votes

0

answers

44

views

Can octonions be represented by infinite matrices?

abstract-algebra matrices representation-theory octonions nonassociative-algebras

modified 3 hours ago runway44 5,458

5

votes

0

answers

2k

views

+100

What is the affine space and what is it for?

vector-spaces affine-geometry

modified 3 hours ago DDD4C4U 1,031

8

votes

0

answers

41

views

How to imagine/prove that all of the following pictures are 2-torus?

general-topology differential-geometry algebraic-topology differential-topology

asked 5 hours ago C.F.G 3,977

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