Mathematics Stack Exchange

0

votes

0

answers

19

views

Proving set relation using logical expression

elementary-set-theory proof-writing set-theory

modified 3 mins ago Graham Kemp 103k

1

vote

1

answer

15

views

Let $\Lambda(x)=(\lambda_1x_1,\lambda_2x_n,…)$ be an operator $l_2 \to l_2$. Show its range is closed iff $\inf_{\lambda_k\not=0} |\lambda_k|>0$

functional-analysis

answered 3 mins ago Kavi Rama Murthy 204k

3

votes

3

answers

54

views

How should one understand the “indefinite integral” notation $\int f(x)\;dx$ in calculus?

calculus analysis notation

modified 4 mins ago JonathanZ supports MonicaC 3,224

0

votes

0

answers

7

views

Is my proof for $f$ is convex iff $f$ is monotonically increasing correct?

real-analysis general-topology solution-verification

asked 4 mins ago User31415 369

2

votes

3

answers

3k

views

What are the radial vectors in an ellipse?

geometry

answered 5 mins ago Roger Venable 1

4

votes

1

answer

84

views

$\int_0^1\frac{\ln\left(1-t\right)\ln^3 t}{2-t}dt$

integration definite-integrals harmonic-numbers

modified 7 mins ago Ali Shather 14.8k

0

votes

1

answer

43

views

Evaluating $\sum\limits_{i=\lceil \frac{n}{2}\rceil}^\infty\binom{2i}{n}\frac{1}{2^i}$

power-series

modified 8 mins ago John Omielan 29k

0

votes

2

answers

18

views

Finding the height of a Pyramid where the sides are given by an equation

calculus integration solid-of-revolution

modified 10 mins ago Narasimham 28.4k

0

votes

0

answers

5

views

Cauchy Functional Equation using Laplace transform?

functional-equations

asked 11 mins ago pico 489

0

votes

1

answer

7

views

Help to prove the following inequality with the Matrix Max norm

linear-algebra matrices norm

answered 2 mins ago Azif00 9,437

1

vote

1

answer

20

views

Linearly dependent planes

combinatorics geometry combinations 3d solid-geometry

modified 13 mins ago Batominovski 46.2k

0

votes

0

answers

3

views

Name for line segments connect prefix sum of non-negative vectors?

geometry terminology euclidean-geometry

asked 14 mins ago peng yu 403

2

votes

0

answers

31

views

Proper flat morphism with geometrically connected and smooth generic fiber

algebraic-geometry

modified 15 mins ago KReiser 28.1k

0

votes

0

answers

24

views

Name for “orthogonal eigenvalues” of a matrix

linear-algebra linear-transformations

modified 19 mins ago Mefistocle 45

0

votes

2

answers

15

views

Finding $dy/dx$ and the gradient at a spacific equation

calculus

answered 22 mins ago hamam_Abdallah 48.6k

1

vote

1

answer

28

views

I need to help with a formula to find the length of a line.

geometry

modified 57 secs ago diracsum 29

1

vote

0

answers

20

views

Proof Verification: Baby Rudin Chapter 5 Exercise 2

real-analysis derivatives solution-verification

asked 24 mins ago Ricky_Nelson 855

0

votes

1

answer

31

views

stationary independent increments: f(t+s) = f(t) + f(s), therefore f(t)=ct

stochastic-processes poisson-process

answered 34 mins ago Mikael Helin 33

1

vote

2

answers

41

views

Financial Mathematics : Annuity loan with a different first period?

finance

modified 36 mins ago Johan 111

2

votes

0

answers

70

views

Constructing the orthocenter of a triangle, using a device that can only draw perpendicular bisectors

contest-math euclidean-geometry triangles plane-geometry geometric-construction

modified 39 mins ago Narasimham 28.4k

0

votes

1

answer

23

views

Is there a simple-ish function for modeling seasonal changes to day/night duration and height of the sun?

functions trigonometry continuity

modified 39 mins ago SaganRitual 37

3

votes

1

answer

32

views

How to look for following problem in Ring theory?

abstract-algebra ring-theory maximal-and-prime-ideals integral-domain

modified 41 mins ago Batominovski 46.2k

2

votes

1

answer

33

views

$G$ acts faithfully on $\Omega$, $A\leq G$, $A$ transitive on $\Omega$. Then $|C_G(A)|$ is a divisor of $|\Omega|$.

group-theory finite-groups group-actions

modified 41 mins ago David Craven 1,448

1

vote

1

answer

15

views

Sequence of Lebesgue integrable functions bounded in norm converges pointwise

real-analysis integration functional-analysis measure-theory

answered 42 mins ago Mark 21.7k

0

votes

0

answers

26

views

Zeros and poles of rational function.

real-analysis calculus complex-analysis solution-verification

modified 44 mins ago Mark Viola 147k

0

votes

4

answers

1k

views

Gaussian distribution probability

probability combinatorics statistics binomial-distribution

answered 47 mins ago Moureen Caroline 1

5

votes

2

answers

60

views

L'hopital rule fails with limits to infinity?

calculus limits

answered 49 mins ago Yves Daoust 177k

1

vote

0

answers

11

views

$\mathbb R$ as continuum many of pairwise disjoint of Bernstein sets

set-theory transfinite-recursion transfinite-induction

asked 49 mins ago 00GB 199

3

votes

0

answers

62

views

What can be concluded about an equilibrium point that has finitely many trajectories that converge to it?

ordinary-differential-equations differential-topology dynamical-systems control-theory stability-in-odes

modified 51 mins ago abc1455 356

5

votes

1

answer

75

views

Invariant $SU(3)$ subgroup for ${\bf 8}$ in ${\bf 3}^* \otimes {\bf 3} ={\bf 1} \oplus {\bf 8}$

abstract-algebra differential-geometry representation-theory lie-groups invariant-theory

modified 52 mins ago annie heart 2,193

1

vote

1

answer

15

views

Linear programming with min/max function

optimization linear-programming maxima-minima

modified 53 mins ago Tortar 586

2

votes

1

answer

58

views

An elementary application of Integral identity

probability inequality expected-value

answered 53 mins ago Daniel Li 2,244

0

votes

0

answers

32

views

Is it an open problem? (Sums of squares)

rational-numbers sums-of-squares open-problem

asked 55 mins ago Danny 19

-2

votes

0

answers

10

views

Novice probability of combinations problem

probability combinations

asked 55 mins ago Nick Robinson 1

-2

votes

0

answers

21

views

Proper Hypothesis Test Setup

probability hypothesis-testing

modified 55 mins ago ecbiz1 1

0

votes

0

answers

6

views

Diagonal of (self) product of doubly stochastic transition matrix

matrices stochastic-processes markov-chains

asked 1 hour ago JoeB 1

0

votes

0

answers

25

views

If $g$ is locally Lipschitz in a compact $C$, then it is here globally Lipschitz too.

real-analysis calculus general-topology analysis lipschitz-functions

modified 1 hour ago Paul Frost 30.6k

2

votes

1

answer

86

views

+50

How does the author derive these relations?

ordinary-differential-equations recurrence-relations

answered 1 hour ago Yuri Negometyanov 17.7k

5

votes

1

answer

43

views

Kernels of commuting linear operators on infinite dimemensional vector space

linear-algebra

answered 1 hour ago Eric Wofsey 242k

0

votes

1

answer

31

views

Two different limits for two similar polar coordinates expressions

calculus limits multivariable-calculus polar-coordinates

modified 1 hour ago user 113k

0

votes

0

answers

5

views

Approximation for definition of stochastic integral

stochastic-integrals approximation-theory

asked 1 hour ago user191919 673

0

votes

1

answer

20

views

Wasserstein gradient flow and continuity equation

functional-analysis partial-differential-equations calculus-of-variations gradient-flows optimal-transport

answered 1 hour ago MaoWao 6,309

1

vote

1

answer

48

views

Is there a specific name for this geometrical shape?

geometry terminology

answered 1 hour ago Jean Marie 45.7k

1

vote

1

answer

51

views

A trick system of equations

systems-of-equations

modified 1 hour ago Steven Van Geluwe 17

1

vote

2

answers

52

views

Calculate Hessian of a “weird” function

multivariable-calculus derivatives

modified 1 hour ago Neal 27.7k

2

votes

1

answer

23

views

Understanding matrix norm and quadratic equations

matrices matrix-norms

modified 1 hour ago Rodrigo de Azevedo 15.7k

1

vote

1

answer

14

views

Orthonormal columns of block matrices expanded with Kronecker products

linear-algebra matrices matrix-equations block-matrices kronecker-product

modified 1 hour ago Rodrigo de Azevedo 15.7k

0

votes

1

answer

18

views

Orthonormal columns of block matrix yield certain property?

linear-algebra matrices matrix-equations block-matrices

modified 1 hour ago Rodrigo de Azevedo 15.7k

2

votes

1

answer

34

views

How to find the set of lines of fixed length connecting two circles?

linear-algebra matrices geometry circles

modified 1 hour ago Rodrigo de Azevedo 15.7k

1

vote

1

answer

20

views

If $\text{ord}_m(c)=n$, find $\text{ord}_m(c^2)$

number-theory elementary-number-theory modular-arithmetic

answered 1 hour ago Mark 21.7k

2

votes

1

answer

34

views

Convergence of $\sum_{n=1}^\infty \frac{(-1)^n}{x^2-n^2}$ in the reals and in the complex numbers

real-analysis sequences-and-series convergence-divergence

answered 1 hour ago Steven Van Geluwe 17

0

votes

0

answers

22

views

Probability Puzzle: The Theater Row

probability combinatorics puzzle

asked 1 hour ago James Bender 330

0

votes

0

answers

32

views

Polar form of $\frac{2(1+i)(1-i\sqrt{3})}{(-\sqrt{3}+i)^{30}}$

complex-numbers

modified 1 hour ago J.G. 77.9k

1

vote

1

answer

33

views

A combination problem with repeated digits such that all the numbers used at least once

permutations combinations

answered 1 hour ago Anatoly 14.1k

0

votes

1

answer

18

views

Csiszar Sum Identity

inequality information-theory

modified 1 hour ago stochasticboy321 3,905

1

vote

1

answer

24

views

$G_\delta$ subset of a $G_\delta$ subset is still a $G_\delta$ subset

general-topology metric-spaces

modified 1 hour ago Azif00 9,437

1

vote

0

answers

12

views

Let $\Phi$ be standard Gaussian CDF and $u > 0$. What is good u-bound for $\int_0^1\Phi(u/r - ur)dr$ as a function of $u$?

real-analysis statistics special-functions gaussian-integral

asked 1 hour ago dohmatob 5,577

1

vote

1

answer

33

views

Cauchy - Schwarz Inequality Random Variables as Vectors

probability-theory cauchy-schwarz-inequality

modified 1 hour ago Anastasis Giannikopoulos 85

0

votes

0

answers

8

views

Map a number range to a unique number or string

real-analysis calculus abstract-algebra

asked 1 hour ago Rami Del Toro 101

3

votes

2

answers

52

views

If $X_n\thicksim\text{Unif}\left\{\frac{1}{n},\frac{2}{n},\dots,\frac{n-1}{n},1\right\}$ then $X_n\overset{d}\to Z$ where $Z\thicksim\text{Unif}[0,1]$

probability-theory probability-distributions solution-verification

modified 1 hour ago Oliver Diaz 6,975

0

votes

2

answers

60

views

If $f(2n)=\frac1{f(n)+1}$ and $f(2n+1)=f(n)+1$ for all $n\in\Bbb N$, then find $n$ such that $f(n)=14/5$.

sequences-and-series functions recurrence-relations functional-equations rational-numbers

answered 1 hour ago PierreCarre 6,478

0

votes

1

answer

17

views

Orthogonal projections of real positive definite matrices and their determinants

linear-algebra matrices eigenvalues-eigenvectors determinant positive-definite

modified 1 hour ago Rodrigo de Azevedo 15.7k

0

votes

0

answers

26

views

Reusing samples from a probability distribution

probability-distributions proof-writing sampling

modified 1 hour ago Alexandru Dinu 329

1

vote

1

answer

23

views

Show that the residue is $c_{-1}=-\frac{q''(z_0)}{(q'(z_0))^3}$.

complex-analysis analysis complex-numbers residue-calculus

modified 1 hour ago Bernard 152k

0

votes

0

answers

10

views

Laplace-Beltrami Operator defined in Conformal Flow of Metrics

partial-differential-equations riemannian-geometry vector-analysis laplacian

asked 1 hour ago Tom 746

1

vote

0

answers

16

views

Relations between two definitions of exponential maps

lie-algebras

modified 1 hour ago Charlie Chang 353

0

votes

1

answer

13

views

If evey linear program can be transformed to an unconstrained problem, then the optimum is unbounded because the objective is linear?

optimization linear-programming constraints

answered 2 hours ago A.G. 2,462

0

votes

0

answers

15

views

Given convex differentiable function $h: R^m \to R$, what is geometric interpretation of $h(x)/\|\nabla h(x)\|$ vis à vis the level-set $h=0$?

real-analysis multivariable-calculus convex-analysis convex-optimization convex-geometry

modified 2 hours ago dohmatob 5,577

1

vote

0

answers

15

views

Large $L$ limit of integral containing $e^{i\omega L(\frac{\pi}{2}-\tau)}$

integration limits analysis mathematical-physics harmonic-analysis

modified 2 hours ago Nicholas Parris 396

0

votes

0

answers

23

views

3-body-problem in python using Euler method

numerical-methods python

asked 2 hours ago Vinzenz Lichtenwallner 21

0

votes

0

answers

19

views

How to define sums of naturals in the context of set theory

elementary-set-theory problem-solving recursion

asked 2 hours ago Iovita Kemény 53

1

vote

0

answers

15

views

p point: an origin of the acronym

terminology forcing

modified 2 hours ago RobPratt 13.7k

0

votes

0

answers

17

views

Completing the square of complicated expression (answer available)

calculus arithmetic completing-the-square

modified 2 hours ago RobPratt 13.7k

1

vote

0

answers

15

views

Concept about marginal probability $p(y)$to conditional probability $p(y|x)$ transformation?

probability probability-distributions conditional-probability marginal-distribution marginal-probability

modified 2 hours ago Samantha 83

0

votes

0

answers

25

views

+50

Correlation between 2 random variables and $\cos(\theta)$ on vector space

vector-spaces random-variables covariance correlation

modified 2 hours ago David 299

2

votes

0

answers

10

views

Extreme points of prefix sum and prefix sum of subsets.

convex-geometry convex-hulls

modified 2 hours ago peng yu 403

1

vote

1

answer

16

views

Eigenvalues of a compact operator with modulus greater than $\epsilon$ is finite

functional-analysis operator-theory c-star-algebras compact-operators

modified 2 hours ago s.harp 15.3k

5

votes

1

answer

151

views

+50

Sum $\sum_{(k_1, k_2, k_3): k_1+k_2+k_3=K, \,\, n_1+n_2+n_3=N}k_1^{n_1}\times k_2^{n_2} \times k_3^{n_3}$

combinatorics number-theory elementary-number-theory bernoulli-numbers bernoulli-polynomials

answered 2 hours ago Sophie 2,686

1

vote

0

answers

35

views

Action of the Fundamental Group of Klein Bottle over $\mathbb{R}^{2}$

abstract-algebra algebraic-topology homology-cohomology fundamental-groups group-cohomology

modified 2 hours ago Batominovski 46.2k

0

votes

3

answers

43

views

Can the function Re$(z^2)$ be approximated uniformly on the unit circle by rational functions having only simple poles?

complex-analysis complex-numbers rational-functions

answered 2 hours ago Blake 2,352

1

vote

1

answer

23

views

Uniqueness of measures related to the Stieltjes transforms

measure-theory moment-problem

answered 3 hours ago Oliver Diaz 6,975

1

vote

0

answers

26

views

Kirby and Siebenmann obstruction for $D \neq 5$?

differential-geometry algebraic-topology differential-topology smooth-manifolds geometric-topology

modified 3 hours ago annie heart 2,193

1

vote

0

answers

11

views

Time continuity of the function in L1 norm i.e. $C([0,T];L^1) $

real-analysis analysis measure-theory lp-spaces total-variation

asked 3 hours ago Rosy 564

2

votes

0

answers

24

views

Schwarz theorem on manifolds

differential-geometry

asked 3 hours ago laura_b 303

0

votes

0

answers

15

views

What does the 'expected value' E represent in mean integrated squared error (MISE)

probability riemann-integration density-function mean-square-error

asked 3 hours ago Metioche 3

0

votes

0

answers

16

views

Clarification of a linear representation of the 2-regular Stern sequence.

sequences-and-series definition

asked 3 hours ago spacebump 1

2

votes

0

answers

34

views

When linear stability doesn't work, can you use higher order Taylor terms?

ordinary-differential-equations taylor-expansion dynamical-systems stability-in-odes

modified 3 hours ago Giraffes4thewin 235

7

votes

0

answers

106

views

Brouwer's fixed point theorem and the one-point topology

general-topology logic category-theory intuition fixed-point-theorems

modified 3 hours ago R. Srivastava 131

2

votes

0

answers

21

views

Characteristic subgroups of extraspecial $2$-groups

group-theory finite-groups p-groups 2-groups

modified 3 hours ago Yasmin 596

1

vote

1

answer

13

views

If $N_k$ is a particular set representing the natural number $k$ and $m \le n$ and set $A= N_m \cup N_n$, then what is the cardinality of set $A$?

set-theory

answered 3 hours ago rpl19 271

0

votes

1

answer

22

views

Calculating second derivatives with curves

differential-geometry

answered 3 hours ago user10354138 20.8k

0

votes

2

answers

1k

views

What is the probability that an element is in a subset of a set?

probability statistics

modified 4 hours ago Sarath M 1

1

vote

1

answer

285

views

Inverse Function Theorem proof: f is injective

functional-analysis multivariable-calculus implicit-function-theorem frechet-derivative inverse-function-theorem

answered 4 hours ago ryan221b 442

0

votes

1

answer

51

views

Any online courses on advanced mathematics subjects?

reference-request education online-resources

modified 4 hours ago HallaSurvivor 6,286

6

votes

2

answers

147

views

If $A$ is a matrix such that $A^T = A^2$, what are eigenvalues of $A$?

linear-algebra matrices eigenvalues-eigenvectors minimal-polynomials transpose

modified 4 hours ago Travis Willse 75.9k

2

votes

0

answers

14

views

Nonlinear dynamics and state space trajectories of networks with time-dependent architecture

graph-theory chaos-theory network non-linear-dynamics multigraphs

asked 5 hours ago Neuroguy 43

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