Mathematics Stack Exchange

2

votes

1

answer

20

views

How to solve the system of such differential equations?

ordinary-differential-equations pde

modified 1 min ago Mariusz Iwaniuk 2,036

0

votes

0

answers

2

views

Milnor's book notation (smooth structure) and its up to date

notation differential-topology

asked 2 mins ago C.F.G 1,792

0

votes

0

answers

11

views

Improper Fourier transform

integration fourier-analysis improper-integrals fourier-transform

modified 2 mins ago Sim 38

0

votes

0

answers

2

views

Jacobian linearization of autonomous ODE at a point on an invariant manifold

ordinary-differential-equations analysis

asked 3 mins ago David 1

0

votes

1

answer

9

views

Convex Set- Intuition

geometry convex-analysis

answered 3 mins ago G. Chiusole 781

2

votes

1

answer

17

views

a question about extension simple topology

general-topology proof-verification

answered 3 mins ago Henno Brandsma 129k

0

votes

1

answer

18

views

Do the positive irrationals form a group with respect to multiplication

abstract-algebra

answered 4 mins ago José Carlos Santos 210k

-1

votes

0

answers

14

views

Shouldn't 'antilogarithm' be called 'logarithm'?

terminology math-history

modified 5 mins ago mjc 67

0

votes

1

answer

15

views

Graph of $f: \emptyset \rightarrow \mathbb{R}$

elementary-set-theory

modified 6 mins ago Shervin Sorouri 714

0

votes

0

answers

11

views

Contour integration with delta functions

contour-integration residue-calculus dirac-delta

modified 7 mins ago Cesareo 12.5k

1

vote

1

answer

32

views

Help with trigonometry right angle triangles problem!

trigonometry

answered 8 mins ago Rick 716

1

vote

1

answer

27

views

Computing Remy Sigrist sequence A279125

sequences-and-series recursion oeis

modified 8 mins ago Calvin Khor 14.3k

1

vote

1

answer

17

views

Show that $\operatorname{spec}(K[x_1,\dots,x_n])=\cup_{L/K}\operatorname{Im}(\psi_L)$ where $\psi_F(a)=\ker(f\mapsto f(a))$

abstract-algebra polynomials extension-field maximal-and-prime-ideals

answered 10 mins ago withoutfeather 365

1

vote

0

answers

12

views

Solution to variational problem

probability calculus-of-variations lagrange-multiplier

modified 10 mins ago piccolo 153

0

votes

0

answers

10

views

Not using Stokes theorem for line integral

calculus multivariable-calculus vector-analysis stokes-theorem

modified 10 mins ago Daniele Tampieri 3,184

0

votes

0

answers

9

views

Trying to understand Grobner basis

linear-algebra abstract-algebra commutative-algebra groebner-basis

modified 11 mins ago Arnaud D. 17.3k

1

vote

2

answers

18

views

Periodicity of recursive sequence

linear-transformations recurrence-relations education

modified 12 mins ago Ethan Bolker 55.1k

0

votes

0

answers

19

views

Direct sum of two subspaces - how to show

linear-algebra direct-sum

modified 12 mins ago Victor Neverland 5

1

vote

0

answers

7

views

Easton’s Lemma in forcing

logic set-theory forcing

asked 14 mins ago mbsq 1,118

1

vote

0

answers

7

views

Placing n distinct varieties of identical objects into k distinct boxes

combinatorics discrete-mathematics

asked 16 mins ago dustbringer 13

1

vote

1

answer

38

views

$f$ is continuous in $a$ if and only if $\lim_{h \to 0} f(a+h) = f(a)$

limits continuity

modified 17 mins ago Ennar 15.4k

0

votes

0

answers

2

views

Completeness of eigenfunctions of Orr-Sommerfeld or Rayleigh stability equation with free surface boundary condition

spectral-theory eigenfunctions stability-theory

asked 19 mins ago allicient 26

1

vote

0

answers

10

views

A counterexample to convergence in $B^2$ implies convergence in $L^2_\text{loc}$

functional-analysis weak-convergence almost-periodic-functions

modified 20 mins ago Bernard 131k

2

votes

3

answers

13

views

Conditional Proof with Negated Disjunctions (Biconditional Premise)

logic natural-deduction

modified 21 mins ago Matthew Daly 2,836

1

vote

1

answer

19

views

Lagrange System of Equations

systems-of-equations

modified 21 mins ago Will Jagy 108k

3

votes

1

answer

46

views

If $(X_n)$ is a martingale, why do we have $\mathbb E[(H\cdot X)_n]=\mathbb E[X_0]$?

probability-theory martingales

modified 22 mins ago bitesizebo 2,286

1

vote

1

answer

25

views

Find a function over natural numbers with specific properties

elementary-number-theory functions natural-numbers

answered 22 mins ago dcolazin 1,880

-1

votes

0

answers

10

views

In calculating depreciation

arithmetic

asked 25 mins ago Ayan Sarkar 1

1

vote

0

answers

19

views

Properties of the sequential space $(X,\tau_{seq})$ generated by $\tau$.

general-topology functional-analysis reference-request calculus-of-variations

modified 25 mins ago BigbearZzz 10.1k

0

votes

0

answers

17

views

Isosceles triangle geometry

geometry

modified 25 mins ago C.F.G 1,792

0

votes

1

answer

15

views

Distributing intersection over vector space addition.

linear-algebra vector-spaces

modified 27 mins ago Kavi Rama Murthy 111k

1

vote

0

answers

8

views

Conditional probability against sum of two normal random variables

probability conditional-probability

asked 27 mins ago Igor Sikora 295

2

votes

0

answers

283

views

+50

Proof explanation: why $\frac{1}{\sqrt 2}$ is optimal?

functional-analysis operator-theory hilbert-spaces examples-counterexamples

modified 29 mins ago BarzanHayati 527

0

votes

0

answers

7

views

cost revenue demand question

implicit-differentiation

modified 29 mins ago José Carlos Santos 210k

0

votes

1

answer

13

views

The interval in which the fractions lies

combinatorics discrete-mathematics

answered 36 mins ago Toby Mak 4,828

2

votes

0

answers

17

views

Does $\int_V f(s)ds=\int_U f(\varphi (t))|\det \varphi '(t))|dt$ hold if $f$ is measurable?

real-analysis integration

asked 42 mins ago user657324 1,067

1

vote

2

answers

23

views

How to evaluate $\int_{1-\sqrt{1-t^2}}^{1+\sqrt{1-t^2}}(y^2-2y+t^2)dy$, where t is constant

calculus integration definite-integrals

modified 43 mins ago Fred 53.5k

1

vote

1

answer

14

views

Proof regarding the existence of elements such that their product is an element of a subgroup

abstract-algebra

modified 44 mins ago Clive Newstead 54.5k

0

votes

0

answers

34

views

Question regarding the similarity of an invertible matrix with its inverse .

linear-algebra matrices eigenvalues-eigenvectors

modified 44 mins ago Rabi Kumar Chakraborty 423

0

votes

1

answer

18

views

Re: Construction of a non-empty perfect set of real numbers without rationals

real-analysis general-topology proof-verification irrational-numbers descriptive-set-theory

answered 46 mins ago Henno Brandsma 129k

1

vote

0

answers

9

views

How many minimum generating sets are there in a finite group?

group-theory

modified 46 mins ago new_bee 106

2

votes

0

answers

12

views

Does Spec functor sends pushouts of rings into pullbacks of sets?

commutative-algebra pullback

modified 52 mins ago Fabio Lucchini 9,787

2

votes

0

answers

14

views

Proof that any commutative family of unbounded self-adjoint operators has a “generating” operator

functional-analysis reference-request operator-theory spectral-theory unbounded-operators

modified 56 mins ago Keen-ameteur 1,800

0

votes

0

answers

5

views

Iterates of isolated closed geodesics

differential-geometry geodesic

asked 57 mins ago Arun 44

2

votes

1

answer

42

views

How to prove the following modulus arithmetic statement?

number-theory modular-arithmetic

answered 1 hour ago Gerry Myerson 152k

7

votes

2

answers

105

views

+50

Every matrix of the centralizer of the centralizer of a matrix is a polynomial in that matrix

linear-algebra matrices polynomials ring-theory

answered 1 hour ago S. Dolan 1,225

1

vote

0

answers

4

views

Derivation of Search Gradients for Natural Evolution Strategies

integration expected-value log-likelihood

asked 1 hour ago mentalmushroom 106

1

vote

1

answer

20

views

$(C_{1}\cup C_{2})^{\perp}=C_{1}^{\perp} \cap C_{2}^{\perp}$, linear code $C_{1}, C_{2}$

linear-algebra finite-fields coding-theory

answered 1 hour ago Federico Fallucca 3,301

-1

votes

0

answers

32

views

Any idea to solve this equation

pde

modified 1 hour ago chuackl 57

2

votes

1

answer

25

views

$\left |\sum_{k=1}^n\epsilon_ke^{ik\theta}\right |\ge \sqrt{n}$

inequality complex-numbers

answered 1 hour ago Kavi Rama Murthy 111k

0

votes

0

answers

8

views

How to approximate this signal with piecewise-linear function?

approximation signal-processing

asked 1 hour ago Eenoku 434

0

votes

0

answers

23

views

Geometry problem of bouncing ball

geometry

asked 1 hour ago Abhinov Singh 149

4

votes

0

answers

22

views

What is the intuition behind Hua’s proof of the Cartan-Brauer-Hua theorem?

abstract-algebra ring-theory intuition division-ring

modified 1 hour ago ysTuan 6

2

votes

2

answers

36

views

Rotating some rectangles to make them horizontal

geometry transformation rotations

modified 1 hour ago Kartoos 40

0

votes

1

answer

10

views

Express two triangle sides based on the given circle equation and the given angle

geometry trigonometry locus

modified 1 hour ago Quanto 2,169

2

votes

0

answers

37

views

The minimal number of elements of a $100-good $ set.

combinatorics number-theory

modified 1 hour ago Asaf Karagila♦ 316k

0

votes

1

answer

10

views

Show that $T\boldsymbol 1_B+M\boldsymbol 1_{B^c}$ is a stopping time if $T$ is a stoping time.

stopping-times

modified 1 hour ago John 346

0

votes

0

answers

4

views

How to determine strip condition of nonlinear PDE?

real-analysis pde

asked 1 hour ago SRJ 2,102

1

vote

0

answers

20

views

Let ABC be acute angled triangle with AB =15 cm and BC=8 cm

geometry

asked 1 hour ago maveric 1,028

0

votes

0

answers

8

views

How to reduce these equations with beta reduction - lambda calculus

lambda-calculus

modified 1 hour ago llamaro25 66

2

votes

1

answer

65

views

Find number of positive integers less than 101 that can't be expressed as difference of squares of two integers.

number-theory

modified 1 hour ago jacopoburelli 302

1

vote

0

answers

17

views

Question about existence of a minimal resolution in the proof of Theorem 19.6 in Matsumura, Commutative Ring Theory

commutative-algebra

modified 1 hour ago C. Fujinomiya 6

0

votes

0

answers

64

views

+50

Sequence problem regarding convergence from an online contest

real-analysis sequences-and-series

modified 1 hour ago Math Guy 302

0

votes

0

answers

35

views

In how many ways can $N$ identical balls be distributed among $3$ persons?

combinatorics permutations

modified 1 hour ago Mars Plastic 3,092

5

votes

2

answers

150

views

The coefficients of a product of monic polynomials are $0$ and $1$; if the polynomials' coefficients are non-negative, must they also be $0$ and $1$?

polynomials factoring

answered 1 hour ago GEdgar 66.3k

1

vote

0

answers

12

views

Are the zero eigenvalues of a Laplacian matrix semi-simple?

linear-algebra matrices graph-theory eigenvalues-eigenvectors graph-laplacian

modified 1 hour ago Rodrigo de Azevedo 13.4k

0

votes

0

answers

11

views

Jacobi Corollary and solving an ODE

ordinary-differential-equations multivariable-calculus determinant trace matrix-exponential

modified 2 hours ago Rodrigo de Azevedo 13.4k

0

votes

2

answers

23

views

Help with algebra in evaluating a limit

calculus algebra-precalculus limits

answered 2 hours ago BarzanHayati 527

4

votes

0

answers

40

views

a version of the famous $n!+1=m^2$ problem

number-theory factorial conjectures square-numbers

modified 2 hours ago tong_nor 2,402

1

vote

1

answer

30

views

Why is my derivation of the variance of a normal distribution incorrect?

probability integration normal-distribution variance

modified 2 hours ago Rodrigo de Azevedo 13.4k

0

votes

0

answers

13

views

Generalized eigenvalue problem for non-singular matrix

linear-algebra eigenvalues-eigenvectors matrix-equations generalized-eigenvector

modified 2 hours ago Rodrigo de Azevedo 13.4k

2

votes

0

answers

16

views

Extension of Goldbach's conjecture to polynomials

elementary-number-theory polynomials goldbachs-conjecture

asked 2 hours ago Trevor 349

1

vote

0

answers

13

views

Saddle point method for a stationary subspace of dimension $> 0$

real-analysis integration functional-analysis laplace-method

modified 2 hours ago Rodrigo de Azevedo 13.4k

3

votes

2

answers

24

views

How to prove the transitivity of relation which is symmetric difference

elementary-set-theory

modified 2 hours ago Andrés E. Caicedo 67k

1

vote

1

answer

15

views

Rauch comparison theorem with other initial conditions?

differential-geometry differential-topology riemannian-geometry

modified 2 hours ago Jack Lee 29.3k

1

vote

1

answer

19

views

Interpretation of solution of pde of form $f(u,v)=0$

real-analysis pde

modified 2 hours ago JJacquelin 48.3k

3

votes

2

answers

21

views

Relation between Triangular Numbers and Combinatorics

combinatorics

modified 2 hours ago BarzanHayati 527

10

votes

0

answers

238

views

+100

An example of a a convolution of singular distribution and a Gaussian distribution that has a 'simple' pdf

probability-theory convolution singular-measures

modified 2 hours ago lonza leggiera 3,369

0

votes

1

answer

13

views

How to apply an 'indicator' function to infinite product?

sequences-and-series infinite-product piecewise-continuity

answered 2 hours ago Ziad Fakhoury 2,006

3

votes

0

answers

56

views

The Ho-Lee Model (1986)

ordinary-differential-equations pde stochastic-processes stochastic-analysis stochastic-pde

modified 2 hours ago koji 45

2

votes

0

answers

43

views

Closed form for $\sum_{n=1}^{m} n^n$

sequences-and-series summation

modified 2 hours ago Ayman Hourieh 32k

7

votes

1

answer

57

views

How wide is the Birkhoff Polytope?

linear-algebra permutations polytopes discrete-geometry birkhoff-polytopes

answered 3 hours ago Daron 5,738

2

votes

1

answer

19

views

Determine whether elements of a set are bounded above, below, or to the side of another in 3 or more directions

matrices elementary-set-theory logic

modified 3 hours ago Ryan Greyling 482

0

votes

2

answers

18

views

Congruence with powers

elementary-number-theory modular-arithmetic

answered 3 hours ago jacopoburelli 302

3

votes

1

answer

18

views

How to transform $(r,s)$ tensor fields?

differential-geometry tensors pullback pushforward

answered 3 hours ago levap 49.4k

4

votes

0

answers

41

views

Find the greatest common divisor of $2^m+1$ and $2^n+1$ that $m,n$ are positive integers.

elementary-number-theory gcd-and-lcm

asked 3 hours ago Isaac YIU Math Studio 382

0

votes

2

answers

31

views

Why are some improper integrals convergent and others divergent?

integration definite-integrals improper-integrals

modified 3 hours ago floyd 105

3

votes

1

answer

89

views

Is the tensor product a reflexive sheaf?

algebraic-geometry sheaf-theory

modified 3 hours ago Alan Muniz 2,979

0

votes

2

answers

38

views

Composition of an integer

combinatorics

modified 3 hours ago Philipp 84

0

votes

2

answers

36

views

Prove if $m$ divides $n$, then $A_n \subseteq A_m$

discrete-mathematics

modified 3 hours ago Martin Sleziak 46.3k

44

votes

0

answers

827

views

+100

Can we remove any prime number with this strange process?

number-theory prime-numbers recreational-mathematics recursive-algorithms

modified 3 hours ago TheSimpliFire 14.8k

10

votes

0

answers

42

views

A nice Combinatorial Identity

real-analysis combinatorics summation

modified 4 hours ago Harmonic Sun 908

0

votes

1

answer

16

views

Inequality of fourier series coefficients

fourier-analysis fourier-series

answered 4 hours ago Surb 42.2k

1

vote

0

answers

35

views

find the minumin of the postive real value $c$ such $x_{1}+x_{2}+\cdots+x_{n}=1$

inequality

modified 4 hours ago inequality 836

1

vote

0

answers

33

views

Is X complete with the given metric d.

general-topology metric-spaces

asked 4 hours ago hi moon 103

5

votes

1

answer

31

views

Clarification: If $R$ is a ring, then $R^n\cong R^m$ as left $R$-modules if and only if they are also isomorphic as right $R$-modules.

abstract-algebra ring-theory modules noncommutative-algebra free-modules

answered 4 hours ago egreg 192k

Explore our Questions