Mathematics Stack Exchange

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+50

Degree of the map $\mathbb{C} \times \mathbb{R} \longmapsto \mathbb{C} \times \mathbb{R}$ $: X(z,t) = (z^2,t)$

differential-geometry manifolds differential-topology smooth-manifolds vector-fields

modified 1 min ago jacopoburelli 3,280

0

votes

0

answers

4

views

Investigate the long-term behaviour of the population? [Leslie Matrices]

linear-algebra matrices

asked 3 mins ago NOTERIC OK 15

0

votes

1

answer

10

views

Find the indicial equation of $x^{3}y''+(cos2x-1)y'+2xy=0$

ordinary-differential-equations

answered 3 mins ago Z Ahmed 30.3k

-1

votes

0

answers

42

views

GUESS THE INTEGER

real-analysis number-theory contest-math

modified 5 mins ago Matti P. 5,381

0

votes

1

answer

11

views

Show that the number of faces in a planar graph on $n$ vertices is bounded from above by $2n-4$

graph-theory

modified 5 mins ago David Scholz 405

3

votes

2

answers

24

views

A subset of the vector space of all real sequences with finitely-many non-zero elements. Boundedness, closedness, compactness and completeness.

functional-analysis solution-verification

modified 7 mins ago leftaroundabout 5,605

0

votes

1

answer

14

views

Importance of Axiom of Extension in Set Theory

elementary-set-theory set-theory

modified 8 mins ago Gae. S. 18.2k

0

votes

1

answer

33

views

Evaluate $\int_{-\infty}^{-1}e^{\lambda t}\operatorname{Log}\left(\frac{\lambda+1}{\lambda}\right)\Bbb d\lambda$

calculus improper-integrals

modified 9 mins ago Kyky 1,465

4

votes

2

answers

4k

views

Find equation of the cone through the coordinate axes and lines $\frac{x}{1}=\frac{y}{-2}=\frac{z}{3}$ and $\frac{x}{3}=\frac{y}{2}=\frac{z}{-1}$.

quadrics

modified 10 mins ago Community♦ 1

2

votes

0

answers

30

views

$\sqrt{x^2+12y}+\sqrt{y^2+12x}=33$ subject to $x+y=23$

algebra-precalculus graphing-functions

modified 11 mins ago Ginger 159

0

votes

0

answers

4

views

Could we define cardinal number on inducible equality?

induction cardinals

asked 13 mins ago Mountain 115

0

votes

0

answers

7

views

how to compute the class group?

quadratic-forms ideal-class-group

asked 14 mins ago Mingshan Zhang 1

-1

votes

1

answer

18

views

How can I merge these functions?

functions

modified 14 mins ago epte 94

0

votes

1

answer

16

views

Is the union of two circles homeomorphic to an interval?

general-topology

answered 14 mins ago Henno Brandsma 183k

0

votes

1

answer

26

views

How to solve a system of a single equation?

linear-algebra matrices systems-of-equations gaussian-elimination

modified 15 mins ago David Scholz 405

0

votes

0

answers

4

views

Rigorously show how a 2D planar rotation in 3D space can be parameterized by theta

linear-algebra

asked 15 mins ago user3180 373

0

votes

1

answer

17

views

Prove that $L^{\infty} [0,1]$ is not separable.

measure-theory lp-spaces

modified 1 min ago Kavi Rama Murthy 239k

0

votes

0

answers

9

views

Untetermined system has infinitely many solutions

matrix-equations

asked 17 mins ago mathslover 365

2

votes

2

answers

28

views

Find constants $a$, $b$, $c$, $d$ and $e$ such that $\cos4x=a\sin^4x+b\sin^3x+c\sin^2x+d\sin x+e$ for all angles $x$

trigonometry

modified 18 mins ago Juan Castaño 223

0

votes

2

answers

43

views

Solution to abstract linear equation system

linear-algebra systems-of-equations

modified 19 mins ago Vajra 1,056

2

votes

1

answer

29

views

Universal set as a collection of objects

elementary-set-theory logic quantifiers

answered 19 mins ago Mauro ALLEGRANZA 82.4k

0

votes

1

answer

31

views

Find $ \lim_{n \to \infty}n \log\left(1+ \left(\frac{f(x)}{n}\right)^p\right)$

limits

modified 22 mins ago Yushiro Aoki 107

0

votes

0

answers

12

views

Can we find an elementary expression for all elementary antiderivatives?

integration algorithms elementary-functions

asked 23 mins ago MethLover 1

0

votes

0

answers

6

views

Regularity of the integral Solution of the Convection-Diffusion equation

real-analysis integration functional-analysis ordinary-differential-equations partial-differential-equations

asked 24 mins ago Djenta 103

0

votes

1

answer

16

views

Find dimension of subspace with condition

linear-algebra linear-transformations

answered 25 mins ago Anonymath 71

0

votes

0

answers

8

views

Does the perimeter of a double integral over a region converge to the perimeter of the original region?

calculus multivariable-calculus iterated-integrals

asked 25 mins ago Johan 1

0

votes

0

answers

16

views

“Flat chain complex”?

abstract-algebra commutative-algebra homological-algebra

modified 26 mins ago leoli1 2,327

0

votes

0

answers

5

views

proving/disproving center, tangent-asymptote intercepts, and normal-axes intercepts are concyclic

asymptotics conic-sections hyperbolic-geometry

asked 28 mins ago I_love_maths 73

-1

votes

0

answers

6

views

Construct a rational expression

rational-numbers

asked 28 mins ago LrleeSuk 1

1

vote

0

answers

69

views

$m ∈ M$ such that the image in $M_{\mathfrak{p}}/\mathfrak{p}M_{\mathfrak{p}}$ is not zero

ring-theory vector-spaces commutative-algebra localization

modified 32 mins ago user26857 42.7k

0

votes

2

answers

20

views

Is this rewriting possible?

calculus algebra-precalculus education

answered 35 mins ago Aryan Bhaskar 1

1

vote

1

answer

18

views

Define the following residue for using the residue theorem

complex-analysis residue-calculus

modified 37 mins ago mag 931

0

votes

1

answer

23

views

Question on marginal probability density function

probability integration probability-distributions conditional-probability

modified 39 mins ago tommik 14.6k

0

votes

0

answers

11

views

How to derive the kth coefficient standard error?

statistics regression standard-error

modified 40 mins ago Jay 53

0

votes

0

answers

14

views

Prove that $\{x\} \times B \in R^{n} \times R^{m} $ is compact, when $B \in R^{m} $ is compact.

multivariable-calculus

modified 41 mins ago Mathaddict 1,886

0

votes

1

answer

41

views

Comparing two large polynomials

polynomials

modified 41 mins ago lonza leggiera 11.3k

2

votes

2

answers

54

views

prove or disprove $(x+1)^{2p^2}\equiv x^{2p^2}+\binom{2p^2}{p^2}x^{p^2}+1\pmod {p^2}$

number-theory

modified 42 mins ago John Omielan 33.8k

0

votes

1

answer

8

views

Norm/Mesh of partitions in multiple integrals

multivariable-calculus multiple-integral

modified 45 mins ago RRL 74.4k

1

vote

1

answer

45

views

What is $\sum _{i, j} \omega ^{i} \wedge \iota (e_{j}) R(e_{i}, e_{j}) \omega$?

differential-geometry proof-explanation riemannian-geometry partial-derivative differential-forms

modified 48 mins ago user454229 163

5

votes

2

answers

3k

views

Countable product of first countable Spaces is first countable

general-topology

modified 49 mins ago Brian M. Scott 548k

1

vote

0

answers

11

views

Twisted conjugacy class for outer automorphism group of $S_{6}$

abstract-algebra group-theory

modified 49 mins ago HallaSurvivor 11.8k

2

votes

1

answer

19

views

Minimizing lower semicontinuous extended-real functions

general-topology functional-analysis optimization solution-verification semicontinuous-functions

answered 49 mins ago daw 34.7k

0

votes

0

answers

7

views

Impact of stepsize in case of numerical integration

calculus integration probability-theory numerical-calculus

asked 51 mins ago Voeslauer123 21

1

vote

1

answer

29

views

Could we evaluate these two indefinite integrals?

calculus integration indefinite-integrals

answered 58 mins ago Parcly Taxel 78.3k

0

votes

1

answer

11

views

Proof Verification: Nested Interval Theorem $\implies$ Completeness of $\mathbb{R}$

real-analysis analysis solution-verification

answered 59 mins ago Anonymath 71

0

votes

1

answer

33

views

Is $\mathbb{R}^J$ metrizable for $J$ uncountable?

general-topology

answered 1 hour ago Henno Brandsma 183k

0

votes

0

answers

14

views

Invertible polynomial

real-analysis polynomials inverse

asked 1 hour ago Nik 33

0

votes

1

answer

23

views

Picard group of a Parabolic subgroup subgroups of a simple or reductive algebraic group.

algebraic-geometry algebraic-groups

answered 1 hour ago Nicolas Hemelsoet 7,501

0

votes

0

answers

18

views

What is the relationship between an existential statement $\exists(x)\varphi(x)$ and the phrase “can be calculated”?

elementary-set-theory first-order-logic ordinals

asked 1 hour ago S.Cramer 2,307

0

votes

1

answer

32

views

How to determine which probability distribution this distribution is closest to?

statistics probability-distributions

modified 1 hour ago StubbornAtom 12.6k

1

vote

1

answer

46

views

Mathematical philosophy

book-recommendation philosophy

answered 1 hour ago J. W. Tanner 53.4k

0

votes

0

answers

8

views

Submersion between smooth manifolds and horizontal vector fields

differential-geometry riemannian-geometry smooth-manifolds

asked 1 hour ago user302934 1,368

0

votes

2

answers

21

views

How to write the negation of a biconditional?

discrete-mathematics logic propositional-calculus

modified 1 hour ago Pedro Amaral 601

7

votes

1

answer

71

views

Looking for a proof of a unexpected combinatorial result.

combinatorics permutations integer-partitions

modified 1 hour ago Calvin Lin 52.8k

1

vote

1

answer

21

views

Show that every homeomorphism is a local homeomorphism

general-topology

modified 1 hour ago Henno Brandsma 183k

1

vote

1

answer

28

views

Gradient of dot product

vector-analysis

modified 1 hour ago Vercassivelaunos 6,245

3

votes

0

answers

83

views

A matrix cannot be expressed as a sum $B+C$ with $B^2=B$ and $C^3=0$

linear-algebra

modified 1 hour ago user8675309 4,400

6

votes

0

answers

87

views

Are there more learnable but undecidable cases except the halting problem

computability

modified 1 hour ago Mountain 115

0

votes

0

answers

8

views

$\text{diag}(M^t,\ldots,M^t)=[\text{diag}(M,\ldots,M)]^t$ with $t$ is real and $M$ is a positive operator

functional-analysis operator-theory

asked 1 hour ago Schüler 3,214

0

votes

0

answers

6

views

Relationship between class group and the set of reduced primitive forms.

quadratic-forms ideal-class-group

asked 1 hour ago Mingshan Zhang 1

3

votes

0

answers

56

views

Let $G$ a group show and $x\in G$ show that $x^{n+m}=x^nx^m$

group-theory solution-verification

modified 1 hour ago Arturo Magidin 320k

2

votes

2

answers

31

views

Solve $(1+x) d y-y d x=0$

ordinary-differential-equations

answered 1 hour ago GReyes 8,418

0

votes

0

answers

12

views

What is “progressive” about progressively measurable processes?

measure-theory stochastic-processes soft-question

modified 1 hour ago Kaira 378

0

votes

0

answers

9

views

Total Derivative Notation and Optimization

calculus multivariable-calculus derivatives optimization

modified 1 hour ago CBBAM 377

2

votes

0

answers

60

views

Is $\mathbb{Z}[i,\varphi]$ a Euclidean domain?

ring-theory gcd-and-lcm euclidean-algorithm euclidean-domain

modified 1 hour ago zjs 410

1

vote

1

answer

38

views

Partition $3n$ people into $n$ groups of $3$ people with conditions

combinatorics

answered 1 hour ago Nico Terry 77

3

votes

1

answer

19

views

Expectation value of area of triangle in a sphere $\mathbb{S}^2$

euclidean-geometry spherical-geometry

answered 1 hour ago RavenclawPrefect 5,421

0

votes

0

answers

8

views

Connections between Levy Processes and Exponential Families

probability-theory stochastic-processes levy-processes

asked 1 hour ago Wasserstein's Apprentice 87

1

vote

1

answer

11

views

Suppose that typically 3/10 of the customers order “grande” mocha. Assume that customers are independent.

probability combinatorics binomial-distribution

modified 1 hour ago oliverjones 2,977

1

vote

2

answers

27

views

Show that $\langle X\rangle$ is a subgroup of $G$

group-theory

modified 1 hour ago Mike 9,430

0

votes

0

answers

20

views

Help understanding: Expected value conditioned on partition

probability-theory statistics conditional-expectation

modified 1 hour ago StubbornAtom 12.6k

1

vote

0

answers

18

views

Uniqueness of the maximal independent sigma algebra?

probability-theory measure-theory statistics

modified 2 hours ago StubbornAtom 12.6k

0

votes

1

answer

10

views

Area of polyhedral surface vs area of its shadow

convex-geometry spherical-geometry

answered 2 hours ago RavenclawPrefect 5,421

0

votes

0

answers

20

views

Prove that the function is convex

optimization convex-analysis convex-optimization nonlinear-optimization

modified 2 hours ago TexanMathemetician85 21

0

votes

0

answers

6

views

$y = \beta_0 + \beta_1 x_1 + \dots + \beta_p x_p$, unknowns $(x_1, \dots, x_p, y)$: Describes a hyperplane of affine space $\mathbb{R}^{p + 1}$?

affine-geometry

asked 2 hours ago The Pointer 4,165

2

votes

2

answers

28

views

How to perform vertical line test algebraically?

functions graphing-functions

modified 2 hours ago M. Nestor 2,144

1

vote

1

answer

23

views

The equivalence of a 2 by 2 positive semidefinite matrix and a 3 by 3 positive semidefinite matrix?

linear-algebra positive-semidefinite semidefinite-programming linear-matrix-inequality

modified 2 hours ago M.A.N 350

3

votes

0

answers

150

views

A problem related to minimizing the multiplication signs

optimization algorithms matrix-decomposition substitution research

modified 2 hours ago hd_30102 61

12

votes

3

answers

28k

views

Conditions for distinct real roots of cubic polynomials.

polynomials

modified 2 hours ago bubba 35.3k

1

vote

2

answers

33

views

Prove that the variance of the MLE of $f(x\mid\theta)=θx^{θ−1}$ tends to $0$ for large $n$

statistical-inference maximum-likelihood

answered 2 hours ago Daman 1,722

9

votes

1

answer

2k

views

Is there a symbol for the antidiagonal matrix that has 1 as every entry?

matrices

modified 2 hours ago bruce 11

3

votes

2

answers

42

views

Find surface area of cylinder $y^2 + z^2 = 1$ between two planes: $x + y - 2 = 0$ and $x-z+4 = 0$.

calculus

answered 2 hours ago Quanto 48k

0

votes

1

answer

10

views

Question about repertoire method example: performing linear combinations.

linear-algebra discrete-mathematics

answered 2 hours ago Jens Schwaiger 2,811

2

votes

0

answers

18

views

Exterior power of lie algebra representation in coordinates

linear-algebra representation-theory lie-algebras

asked 3 hours ago bark 103

0

votes

0

answers

21

views

Proof of stable matching

algorithms proof-explanation

modified 3 hours ago David Scholz 405

0

votes

0

answers

5

views

Dominance matrix for games with multiple participants

matrices matrix-rank

asked 3 hours ago Waytrader 1

0

votes

0

answers

11

views

Minimizing the Second Smallest Value

optimization

asked 3 hours ago rianko 1

1

vote

0

answers

12

views

Geometry interpretation of any continuous random variable

multivariable-calculus probability-distributions

modified 3 hours ago Ryan Chen 111

0

votes

1

answer

20

views

Triangulation of 2-Manifolds

general-topology algebraic-topology manifolds

answered 3 hours ago j.q. 11

0

votes

0

answers

9

views

Elliptic regularity estimate for Possion with bounded forcing term

partial-differential-equations harmonic-functions regularity-theory-of-pdes elliptic-equations holder-spaces

asked 3 hours ago msm 2,500

0

votes

1

answer

14

views

Calculating an angle of incidence of a ray on a curved surface

geometry trigonometry

answered 3 hours ago Joshua Wang 3,452

1

vote

0

answers

12

views

Prove that a probability measure on $\mathcal{B}[0,1]$ and lebesgue measure are mutually singular

measure-theory lebesgue-measure

asked 4 hours ago José Leonel 85

1

vote

1

answer

35

views

Product in the Category of $L$-structures with Homomorphisms.

category-theory model-theory

modified 4 hours ago Atticus Stonestrom 3,978

3

votes

0

answers

32

views

Deriving the equation of the polar axis-aligned ellipsoid

geometry inequality convex-analysis cauchy-schwarz-inequality convex-geometry

modified 4 hours ago strawberry-sunshine 3,517

0

votes

0

answers

11

views

Embedding a bivariate normal distribution in $\mathbb{R}^3$

linear-algebra normal-distribution quadratics quadratic-forms covariance

modified 5 hours ago Museful 751

0

votes

0

answers

30

views

Dummit & Foote 1.7.12 - finding a nicer expression for $r^xs^y\cdot a$ for $a\in A$

abstract-algebra proof-writing

modified 5 hours ago strawberry-sunshine 3,517

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