Mathematics Stack Exchange

2

votes

1

answer

590

views

Sigmoid Function Question

functions exponential-function

modified 2 mins ago Davos 101

1

vote

1

answer

5

views

How many words can be formed by taking four letters at a time out of the letters of the word MATHEMATICS?

combinatorics permutations

modified 2 mins ago N. F. Taussig 47.6k

-1

votes

3

answers

24

views

Prove if next series are absolute convergent

sequences-and-series

answered 3 mins ago cip999 1,452

0

votes

0

answers

2

views

Question about Shapiro Lemma

group-cohomology class-field-theory

asked 3 mins ago Great Dick 8

0

votes

0

answers

11

views

Alexander Duality Theorem, a simple version in $\mathbb{R}^n$

general-topology algebraic-topology

modified 5 mins ago Hulkster 901

0

votes

2

answers

35

views

Probability that a normal random variable is greater than the maximum of $n$ i.i.d. random variables

probability-theory random-variables normal-distribution extreme-value-theorem

answered 5 mins ago DariusTheGreat 107

7

votes

1

answer

41

views

A question about groups of order $504$

group-theory finite-groups sylow-theory

answered 5 mins ago Bach 2,676

0

votes

1

answer

9

views

zeta function-deriving reflection equation from functional equation

riemann-zeta

answered 5 mins ago phy_math 1,676

3

votes

3

answers

2k

views

Time derivative of curl

calculus vectors vector-analysis

answered 6 mins ago Slobodan Nedic 1

0

votes

1

answer

6

views

Uniform convergence of a continuously parametrized family of functions

real-analysis analysis convergence uniform-convergence

answered 7 mins ago Kavi Rama Murthy 102k

1

vote

1

answer

22

views

Greatest product (Using Calculus)

calculus maxima-minima

answered 9 mins ago 5xum 95.3k

0

votes

0

answers

3

views

Do there exist $0<b<a$ such that ${}_1\!F_1(a, b; -x)$ is nonnegative for $x >0$?

probability-distributions special-functions

asked 11 mins ago Stéphane Laurent 795

3

votes

0

answers

41

views

Immersions whose images are actually submanifolds? Or surjective immersions? (I think surjective immersions are local diffeomorphisms)

general-topology differential-geometry manifolds differential-topology

modified 11 mins ago Selene Auckland 550

0

votes

0

answers

13

views

Are open subsets of immersed submanifolds immersed submanifolds?

general-topology proof-verification differential-geometry differential-topology submanifold

modified 13 mins ago Selene Auckland 550

0

votes

0

answers

4

views

A variant of selectivity for ultrafilters on $\mathbf{N}$

logic reference-request set-theory filters

asked 14 mins ago Paolo Leonetti 11.4k

1

vote

1

answer

25

views

Proving the Triangle Inequality using only the Axioms of Inequality on the set of Real Numbers

real-analysis inequality proof-writing absolute-value axioms

modified 14 mins ago Wuestenfux 8,754

2

votes

1

answer

46

views

Requesting Proof Verification of a Strict Inequality

proof-verification inequality

modified 18 mins ago nmasanta 2,918

0

votes

0

answers

9

views

Estimating $n_0$ such that $f^n (x) \in [1+2\sigma, \infty)$, $\forall\ n>n_0$. Where $f(x) = x^3 + \frac{2}{3 \sqrt{3}} + \varepsilon$.

real-analysis dynamical-systems ergodic-theory

modified 19 mins ago Matheus Manzatto 1,465

0

votes

0

answers

7

views

Are open local embeddings equivalent to local diffeomorphisms? (Do not use immersions)

general-topology differential-geometry manifolds differential-topology retraction

asked 20 mins ago Selene Auckland 550

0

votes

1

answer

9

views

PDF and CDF in joint probability distribution

probability integration probability-distributions

modified 23 mins ago Kavi Rama Murthy 102k

0

votes

0

answers

8

views

Dimension of domain is greater than/less than/equal to dimension of range for a smooth surjection/injection/submersion/immersion?

general-topology differential-geometry manifolds differential-topology retraction

asked 29 mins ago Selene Auckland 550

0

votes

1

answer

10

views

Let P be a singly linked list. Let Q be the pointer to an intermediate node x in the list.

sequences-and-series

answered 33 mins ago TheCoolDrop 370

3

votes

1

answer

22

views

Does $\int_{\mathbb R}x^2f_X(x)dx=\int_{\mathbb R}x^2f_X(x)^2dx$ or are they comparable?

measure-theory

modified 35 mins ago Feng Shao 2,446

0

votes

0

answers

11

views

Tensor-valued differential forms

differential-geometry manifolds differential-forms tensors

asked 35 mins ago Kcronix 110

-1

votes

0

answers

9

views

Convergence of infinite series arithmetic mean of random variables

statistics

asked 36 mins ago Murali 1

0

votes

0

answers

17

views

Show that rank$(L_{A^t})$ = rank$(L_A)$

linear-algebra

modified 40 mins ago user1230403 866

0

votes

0

answers

29

views

Where can I find the errors list of “Principles of Algebraic Geometry” written by Phillip Griffths and Joseph Harris?

algebraic-geometry

modified 40 mins ago Born to be proud 996

5

votes

1

answer

35

views

What is the most common and appropriate definition of tensor?

tensors

modified 41 mins ago Adam Latosiński 6,814

0

votes

1

answer

15

views

Example of a stochastic process $X_t$ such that given condition holds

probability probability-theory stochastic-processes stochastic-calculus

answered 46 mins ago Kavi Rama Murthy 102k

0

votes

0

answers

9

views

Functional Derivative of Exponential

derivatives

asked 46 mins ago clearseplex 34

1

vote

0

answers

23

views

Number of natural numbers smaller than a given natural number!

number-theory algebraic-number-theory

asked 48 mins ago Dino 136

4

votes

0

answers

78

views

+50

How to bound this integral with the Hardy-Littlewood maximal function

real-analysis harmonic-analysis potential-theory

modified 49 mins ago Tim Dikland 456

2

votes

1

answer

21

views

In how many ways can we place $10$ identical red balls and $10$ identical blue balls into $4$ distinct urns if there are no constraints?

combinatorics

modified 51 mins ago N. F. Taussig 47.6k

0

votes

1

answer

15

views

General Query of Exponential Distribution

probability

answered 55 mins ago schalange 11

0

votes

1

answer

23

views

Increase angle from first to second quadrant, and then decrease it from third to fourth

trigonometry

answered 56 mins ago VansFannel 128

1

vote

0

answers

47

views

Integral of a special combination of polynomial and exponential functions

calculus integration polynomials exponential-function

modified 58 mins ago Shabnam 6

0

votes

1

answer

23

views

Find displacement $x$ given $\ddot x=t^2e^{-t}$ with $\dot x(0) =10$ and $x(0)=0$

calculus physics classical-mechanics

answered 1 hour ago Fred 52k

3

votes

0

answers

24

views

What is the growth rate of the products of binomial coefficients?

sequences-and-series combinatorics number-theory summation binomial-coefficients

modified 1 hour ago Nilotpal Kanti Sinha 5,564

-1

votes

1

answer

33

views

Linear transformation and defining a new function

linear-algebra matrices

modified 1 hour ago TheSimpliFire 14.5k

0

votes

0

answers

7

views

Any precise method for solving linear systems with ill-conditioned matrices

real-analysis linear-algebra systems-of-equations condition-number

asked 1 hour ago Bigi Varghese Philip 20

0

votes

1

answer

16

views

Theoretical question regarding differential equations with various options

ordinary-differential-equations

answered 1 hour ago Jan 1,264

0

votes

1

answer

21

views

AXBYC matrix product find XY

linear-algebra optimization matrix-equations kronecker-product

answered 1 hour ago Florian 1,722

0

votes

1

answer

34

views

How to get foot of prependicular by 3 coordinates 3D

geometry 3d

answered 1 hour ago Jean Marie 34.1k

1

vote

0

answers

39

views

+50

Prime ideals lying over a P.I.D

abstract-algebra ideals integral-extensions

modified 1 hour ago Keen-ameteur 1,729

0

votes

7

answers

52

views

Give an example of a closed set which is not compact.

real-analysis general-topology analysis

modified 1 hour ago Kavi Rama Murthy 102k

1

vote

0

answers

29

views

Trouble understanding how a big-o bound proves a limit

number-theory limits asymptotics

modified 1 hour ago zhoraster 16.2k

0

votes

0

answers

48

views

Can $\Bbb Z_n$l ideals be generated by one element?

abstract-algebra ring-theory ideals

modified 1 hour ago se-hyuck yang 247

2

votes

0

answers

8

views

Measurability of probability densities as maps from a parameter space

real-analysis probability-theory bayesian density-function measurable-functions

asked 1 hour ago Jack London 366

0

votes

2

answers

20

views

Solving differential equation by using Bernoulli method

ordinary-differential-equations

modified 1 hour ago nmasanta 2,918

0

votes

1

answer

11

views

Elementary question on multilinearity of differential forms

differential-forms

answered 1 hour ago Matt 2,954

0

votes

0

answers

6

views

What is the system state of the random splitting of a markovian arrival process?

stochastic-processes markov-process

asked 1 hour ago lightcruiser 1

3

votes

1

answer

39

views

proof of combinatorial identity using given identities

combinatorics

answered 1 hour ago Markus Scheuer 66.8k

0

votes

1

answer

23

views

Probability for k events in an arbitrary time step, while no events before

probability statistics poisson-distribution binomial-distribution

modified 1 hour ago HighwayJohn 130

0

votes

1

answer

28

views

Given a conditional probability P(B|A), is it reasonable to consider B and A are independent?

probability statistics markov-chains machine-learning bayesian

modified 1 hour ago czlsws 175

0

votes

1

answer

19

views

Questioning the rules of radicals

radicals

modified 1 hour ago nmasanta 2,918

-2

votes

2

answers

36

views

How does this answer follow?

real-analysis

modified 1 hour ago Niki Di Giano 1,030

0

votes

1

answer

1k

views

Sub sigma algebra and probability spaces — definition

real-analysis probability measure-theory probability-theory

modified 1 hour ago user398843 760

3

votes

5

answers

8k

views

Complex functions and modulus

complex-analysis complex-numbers

answered 1 hour ago eyeballfrog 9,688

1

vote

0

answers

14

views

1D-Biased Random Walk Hitting Time Distribution

probability probability-distributions random-walk stopping-times

modified 2 hours ago ForgotEverything 6

0

votes

1

answer

12

views

Negation of Non-Increasing order and Non-decreasing ordera

sequences-and-series first-order-logic

modified 2 hours ago Klangen 2,294

3

votes

0

answers

18

views

Epimorphisms of schemes

category-theory schemes affine-schemes

asked 2 hours ago A. Smith 26

1

vote

0

answers

14

views

Isomorphism of sheaves of rings

algebraic-geometry sheaf-theory schemes affine-schemes

asked 2 hours ago Milka 6

1

vote

0

answers

23

views

How to solve differential equation involving dot product of vectors?

calculus ordinary-differential-equations vectors

asked 2 hours ago George Tian 207

0

votes

0

answers

15

views

A proof question of an inequality concerning information theory

inequality information-theory

modified 2 hours ago Peter Nova 42

0

votes

1

answer

29

views

Matlab: Creating matrix of values of a function without loops

matlab

modified 2 hours ago Hawraa Abbas 6

1

vote

0

answers

9

views

An injective immersion is an embedding if and only if open onto image if and only if image is (regular) submanifold?

general-topology proof-verification differential-geometry differential-topology submanifold

asked 2 hours ago Selene Auckland 550

0

votes

1

answer

19

views

Domain of the derivative

multivariable-calculus derivatives differential-geometry tangent-spaces

modified 2 hours ago José Carlos Santos 202k

0

votes

0

answers

40

views

+50

d_fold Veronese Embedding

algebraic-geometry projective-geometry affine-geometry

modified 2 hours ago B.K-Theory 163

1

vote

0

answers

12

views

locally constant $\mathbb{Q}_l$-sheaf from an $A$-torsor.

algebraic-geometry algebraic-number-theory arithmetic-geometry

modified 2 hours ago Sameer Kulkarni 934

0

votes

5

answers

185

views

Can an infinite group have a finite number of elements with order $k$?

group-theory examples-counterexamples infinite-groups

modified 2 hours ago TheSimpliFire 14.5k

1

vote

0

answers

12

views

Tour a $M\times N$ chess board with a piece that moves in each turn along the diagonal of a $m\times n$ rectangle

number-theory elementary-number-theory chessboard

modified 2 hours ago arax 1,477

3

votes

2

answers

40

views

Every metric space can be isometrically embedded in a Banach space.

functional-analysis banach-spaces

answered 2 hours ago M. A. SARKAR 2,573

0

votes

0

answers

8

views

i do not understand runge kutta method of local truncation

numerical-methods

asked 2 hours ago seyunkim 6

2

votes

1

answer

37

views

Prove $\angle1\cong\angle4$

geometry proof-verification

modified 2 hours ago harpey1111 80

1

vote

0

answers

15

views

Where's my mistake in this closed formula for homogeneous linear recurrence equations?

discrete-mathematics recurrence-relations generating-functions

asked 3 hours ago Sudix 1,386

0

votes

0

answers

22

views

May I assume that an undefined fraction has a denominator equal to 0?

algebra-precalculus trigonometry

asked 3 hours ago Ziscmac 1

0

votes

0

answers

11

views

Need help on solving inequalities number line

inequality education

asked 3 hours ago MyOldCookie 3

0

votes

1

answer

12

views

Having problem with the particular equation of 2nd order non-homogeneous differential equations

calculus ordinary-differential-equations

modified 3 hours ago LutzL 66.1k

0

votes

1

answer

16

views

Row Echelon Form - Change of basis

linear-algebra abstract-algebra matrices

answered 3 hours ago José Carlos Santos 202k

1

vote

1

answer

29

views

Examples of self adjoint compact operators on Hilbert spaces

functional-analysis hilbert-spaces big-list

answered 3 hours ago daw 26.4k

0

votes

0

answers

10

views

Discretise 1D Boltzmann Transport Equation with Discrete Ordinates (Sn) - Finite Element Method (CG-FEM)

numerical-methods finite-element-method transport-equation

modified 3 hours ago nikjohn 101

0

votes

0

answers

10

views

When can you determine the cardinality of the compliment of the union of the proper subsets?

elementary-set-theory

asked 3 hours ago user3146 68

0

votes

0

answers

12

views

matrix multiplication ,which each element in this matrix is matrix too .$\mathbf P\mathbf P^H = \frac{P}{t} \mathbf I$

matrices matrix-calculus

modified 3 hours ago XM551 147

5

votes

1

answer

71

views

Surface Area of $n$-Dimensional Sphere with Multiple Hyperplanar Cuts

geometry multivariable-calculus differential-geometry vector-analysis spheres

modified 3 hours ago mr_e_man 1,285

0

votes

0

answers

7

views

Product distribution of X and Y where X is exponentially distributed and Y|X is normally distributed

statistics probability-distributions conditional-probability

asked 3 hours ago John 1

1

vote

0

answers

18

views

On the minimal polynomial of constructible numbers

abstract-algebra

asked 3 hours ago André Porto 925

0

votes

0

answers

15

views

particular solution of differential equation which $g(t)$ is dirac delta function

ordinary-differential-equations

modified 3 hours ago Daniele Tampieri 3,102

1

vote

0

answers

15

views

Zeroes of real analytic functions of several variables

real-analysis complex-analysis roots analytic-functions

asked 3 hours ago Riley 187

0

votes

0

answers

11

views

Is the 2-Category of Groupoids Locally Presentable?

category-theory groupoids locally-presentable-categories accessible-categories

modified 3 hours ago Arnaud D. 17k

1

vote

1

answer

12

views

Constructing 90% confidence interval for standard deviation on Matlab

statistics matlab statistical-inference

modified 3 hours ago BruceET 37.4k

0

votes

0

answers

11

views

Prove that an infinite chain contains either a chain order-isomorphic to the positive integers

order-theory

asked 4 hours ago Bazar Tumurkhan 1

1

vote

3

answers

52

views

Question on Radicals

radicals fractions rationalising-denominator

modified 4 hours ago C. Melton 192

2

votes

0

answers

13

views

Projecting onto triangle - nonlinear simultaneous equation

nonlinear-system discrete-geometry

modified 4 hours ago Paul Childs 601

4

votes

1

answer

20

views

Monotonicity of function involving ratios of modified Bessel function of first kind

real-analysis special-functions bessel-functions approximation-theory

answered 5 hours ago Robert Israel 344k

1

vote

1

answer

93

views

When is $f(x) = g(x) \mod 2^k$ an odd permutation?

combinatorics reference-request permutations

modified 5 hours ago user326210 10.8k

6

votes

4

answers

166

views

The closed-form solution of the family $\sum_{n=1}^{\infty} \sum_{m=1}^{\infty} \frac{1}{nm(pn+m)}$?

integration definite-integrals closed-form constants experimental-mathematics

modified 5 hours ago Tito Piezas III 29.7k

Explore Our Questions