Mathematics Stack Exchange

1

vote

0

answers

16

views

Is the first dual equal to the third dual of a vector space

vector-spaces dual-spaces

modified 3 mins ago mathew 1,186

0

votes

0

answers

21

views

Make Eigenvalues in the left half plane (Complex domain analysis)

complex-analysis eigenvalues-eigenvectors eigenfunctions

modified 3 mins ago Jenny Y 1

0

votes

1

answer

23

views

Bounding coefficients of the polynomial $(1-x^2)^n (1-x)^{-m}$.

analysis binomial-coefficients approximation upper-lower-bounds negative-binomial

answered 3 mins ago Tuvasbien 3,002

1

vote

1

answer

32

views

Motivation for $3\times 3$ matrix inverse formula

linear-algebra intuition

answered 4 mins ago Bernard 152k

1

vote

1

answer

14

views

A problem to show that a certain field extension is not normal

field-theory extension-field minimal-polynomials splitting-field normal-extension

modified 5 mins ago Noob mathematician 1,321

0

votes

1

answer

5

views

Decompose $SO(8)$ and $Spin(8)$ 8 dimensional representations to $SO(m)$ and $SO(n)$

group-theory differential-geometry representation-theory lie-groups lie-algebras

answered 1 min ago David A. Craven 2,283

1

vote

2

answers

31

views

When is it possible to “move” an exponent out of a radical?

algebra-precalculus radicals

modified 5 secs ago zwim 17.1k

3

votes

0

answers

50

views

dA in Polar Coords the Wrong Way

integration multivariable-calculus polar-coordinates

modified 7 mins ago StubbornAtom 11.6k

0

votes

1

answer

17

views

Showing Divergence of $\sum\limits_{n=1}^{\infty} \frac{1}{n\ln n + \sqrt{\ln^3n}}$

sequences-and-series

answered 1 min ago user 114k

2

votes

0

answers

17

views

Proof that $(\forall x)(x \in \mathbb{F} \rightarrow x\cdot e = e \cdot x = e)$

real-analysis solution-verification

asked 11 mins ago K.M 2,074

1

vote

0

answers

14

views

Conductance of random walk on a square

probability-theory graph-theory markov-chains

modified 14 mins ago manifolded 2,033

1

vote

0

answers

27

views

Set of any $n$ integers has a subset of $n^{1-o(1)}$ elements with no arithmetic progression [closed]

number-theory discrete-mathematics arithmetic additive-combinatorics

modified 17 mins ago Thomas Andrews 142k

1

vote

0

answers

20

views

Solution of PDE in the sense of multiplication by $\eta \in W^{1,2}_0$ and a uniform boundedness observation

functional-analysis partial-differential-equations calculus-of-variations

modified 21 mins ago Arctic Char 2,533

0

votes

0

answers

8

views

Unification of an expression : Example

logic first-order-logic unification

asked 24 mins ago Wassim Jaoui 23

0

votes

0

answers

13

views

Equivalent properties of graded ideals

abstract-algebra ring-theory commutative-algebra

modified 26 mins ago Michael Morrow 1,275

4

votes

0

answers

50

views

Interpreting $\textbf{PA} + \neg\text{Con}(\textbf{PA})$ in $\textbf{PA}$

logic proof-theory peano-axioms

modified 1 min ago Jori 1,404

0

votes

1

answer

786

views

discrete math: logic, implication and law of excluded middle exemplified

discrete-mathematics logic

modified 27 mins ago Community♦ 1

1

vote

1

answer

9

views

Linear-programming, object function

linear-transformations solution-verification linear-programming problem-solving programming

answered 28 mins ago callculus 24.3k

1

vote

1

answer

18

views

Domain issues in transformation of the coordinate representation of a function

differential-geometry smooth-manifolds mathematical-physics general-relativity special-relativity

modified 28 mins ago peek-a-boo 14k

0

votes

0

answers

16

views

Convergence in Distribution (Probability)

probability-theory probability-distributions convergence-divergence

modified 30 mins ago Darlyn LC 1

0

votes

0

answers

10

views

Non-associativeness of composition in deductive systems?

logic category-theory intuition math-history philosophy

asked 32 mins ago Dry Bones 111

0

votes

1

answer

18

views

Serre-Swan theorem for Hilbert bundles?

differential-geometry vector-bundles

modified 33 mins ago Arctic Char 2,533

0

votes

0

answers

14

views

Shiryaev's proof for the number of combinations with repetition

probability combinatorics combinations

asked 33 mins ago Novice 317

6

votes

4

answers

14k

views

Show that two matrices with the same eigenvalues are similar

linear-algebra proof-verification

modified 34 mins ago Martin Argerami 153k

1

vote

0

answers

19

views

Three Cardinality Problems

elementary-set-theory

modified 35 mins ago Andrés E. Caicedo 71k

1

vote

2

answers

28

views

How do you find the area of the 'floors' in a torus?

calculus geometry analytic-geometry

answered 36 mins ago Narasimham 28.5k

1

vote

1

answer

17

views

Using generating function to solve non-homogenous recurrence relation

discrete-mathematics recurrence-relations generating-functions

answered 38 mins ago Brian M. Scott 510k

0

votes

0

answers

8

views

How do we talk about the “complements” of solids?

geometry geometric-topology polyhedra

asked 38 mins ago Erik G. 795

3

votes

0

answers

39

views

Hessian of $f(X)$ when $X$ is a symmetric matrix

multivariable-calculus taylor-expansion approximation approximation-theory hessian-matrix

modified 39 mins ago Khashayar Baghizadeh 842

4

votes

1

answer

22

views

when is a limit of measure preserving maps also measure preserving?

real-analysis analysis measure-theory weak-convergence ergodic-theory

answered 42 mins ago Stephen Montgomery-Smith 19.7k

0

votes

0

answers

12

views

How do I define this preorder?

notation terminology order-theory

asked 43 mins ago samerivertwice 7,107

1

vote

1

answer

32

views

Finding $\iint_D \frac{10}{ \sqrt {x^2 + y^2}}dx\,dy$ for $D = \{(x,y) \mid 0 \leq x \leq 1, \sqrt{1-x^2} \leq y \leq x\}$

integration multivariable-calculus multiple-integral bounds-of-integration

modified 45 mins ago StubbornAtom 11.6k

1

vote

0

answers

18

views

Diagonal sequences and filters

general-topology filters nets

modified 45 mins ago user558840 369

1

vote

0

answers

11

views

${}^tJ:\mathcal{D}'(\Omega') \to \mathcal{D}'(\Omega)$ is not onto

functional-analysis distribution-theory topological-vector-spaces

modified 46 mins ago Victor Hugo 1,165

0

votes

1

answer

33

views

Evaluating $\iiint z(x^2+y^2+z^2)^{−3/2}\,dx\,dy\,dz$ over the part of the ball $x^2+y^2+z^2\le 81$ defined by $z\ge 4.5$

integration multivariable-calculus spherical-coordinates multiple-integral

modified 48 mins ago StubbornAtom 11.6k

3

votes

1

answer

74

views

+100

Geometry of Riemannian quotient manifold $St(\mathbb{C}^{n \times p},B)/U(1)^{\times p}$

lie-groups riemannian-geometry quotient-spaces

answered 51 mins ago cjferes 1,649

0

votes

0

answers

19

views

How do I show that $\mathbb{E} \max_{i\le N} |X_i| \le CK\sqrt{\log N}$, where $X_i$ are sub-gaussian random variables?

probability probability-theory concentration-of-measure

modified 52 mins ago Xander Henderson 19.9k

2

votes

1

answer

27

views

Is it true that any two of the graphs of cubic functions are similar?

cubic-equations geometric-transformation

modified 52 mins ago Moko19 701

1

vote

1

answer

32

views

Every Riemann integrable function is almost equal to a bounded Lebesgue integrable function.

measure-theory

modified 52 mins ago mathcounterexamples.net 39.3k

-1

votes

0

answers

21

views

Prove that if $x$ is the greatest lower bound of $U$, then $x$ is the least upper bound of $B$.

proof-writing solution-verification

modified 55 mins ago Khashayar Baghizadeh 842

0

votes

1

answer

21

views

Calculate the position of a Euclidean vector given the distances to a set of known vectors

geometry

modified 55 mins ago Make42 699

3

votes

1

answer

37

views

$A,B$ Noetherian rings, $A\subseteq B$ integral extension, $\mathfrak m $ a maximal ideal of $A \implies B/\mathfrak m B$ is Artinian

abstract-algebra commutative-algebra noetherian artinian

modified 1 hour ago Badam Baplan 6,595

3

votes

0

answers

40

views

how do I find derivative of eigenvalues for real, symmetric, positive definite matrix?

linear-algebra eigenvalues-eigenvectors

modified 1 hour ago j. deo 31

0

votes

0

answers

14

views

If $u \in H^1(\Omega)$ with $\Delta u \in L^2(\Omega)^*$, is $u \in H^2(\Omega)$?

functional-analysis partial-differential-equations sobolev-spaces laplacian weak-derivatives

modified 1 hour ago StopUsingFacebook 626

3

votes

0

answers

75

views

Probability of getting off the bus in drinking game “Ride the Bus”

probability combinatorics solution-verification

modified 1 hour ago S. Miner 31

1

vote

0

answers

16

views

Prove that the angles of exactly $4$ vertices of a polygon, with prime number of sides, can form an arithmetic progression

geometry prime-numbers polygons arithmetic-progressions set

asked 1 hour ago Stranger Forever 985

0

votes

0

answers

13

views

If $A$ is PSD, does $B'AB+C'AC = 0$ imply $B'AB=0$ and $C'AC=0$

matrices matrix-equations positive-semidefinite

asked 1 hour ago JDoe2 408

1

vote

1

answer

26

views

Find the eccentricity of the conic $4x^2+y^2+ax+by+c=0$, if it tangent to the $x$ axis at the origin and passes through $(-1,2)$

conic-sections

modified 1 hour ago Math Lover 976

0

votes

0

answers

20

views

Maximum frustration index of the Ising model

graph-theory coding-theory vector-lattices signed-graphs

modified 1 hour ago PeaBrane 241

2

votes

1

answer

38

views

Calculate the sum of this series$\sum_{n\geq 0}^{}a_{n}x^n$

real-analysis calculus sequences-and-series

answered 1 hour ago Isaac Browne 6,330

3

votes

1

answer

36

views

Reparametrization theorem

differential-geometry curves arc-length

modified 1 hour ago Ted Shifrin 81.5k

0

votes

0

answers

22

views

geometric derivation of formulas for conic sections from a double cone

geometry analytic-geometry conic-sections alternative-proof math-history

modified 1 hour ago Joaquin Brandan 629

0

votes

0

answers

7

views

Parametrizing the Intersection of two Generalized Ellipsoids to find Arc Length

geometry multivariable-calculus parametrization quadrics

asked 1 hour ago StackingMonkey 1

0

votes

1

answer

40

views

What are the set theoretic properties of vector spaces?

vector-spaces definition physics

answered 1 hour ago J.G. 78.4k

0

votes

1

answer

22

views

Radius of convergence of series whose nth term coefficient is nth prime

power-series

answered 1 hour ago Brozovic 1,033

3

votes

0

answers

19

views

Does modal replacement hold in modal logic of forcing?

modified 1 hour ago chris scambler 279

3

votes

2

answers

35

views

Integral of Series over Domain of Convergence

integration sequences-and-series convergence-divergence pointwise-convergence

answered 1 hour ago Mark Viola 147k

1

vote

0

answers

25

views

Relationship between row and column range of a matrix

linear-algebra matrices vector-spaces vectors orthogonality

modified 1 hour ago Rodrigo de Azevedo 15.8k

0

votes

0

answers

10

views

About sufficient conditions for very structured positive definite matrices

linear-algebra matrices positive-definite

asked 1 hour ago gradstudent 327

0

votes

0

answers

9

views

Uniformly cauchy in probability gives a uniform upper limit

real-analysis analysis probability-theory measure-theory probability-limit-theorems

asked 1 hour ago nomadicmathematician 5,943

0

votes

0

answers

18

views

calculate expected value of a integral - gaussian distribution

gaussian-integral gaussian

modified 1 hour ago an4s 3,531

0

votes

1

answer

30

views

If $A$ is a positive definite real symmetric matrix and $\lambda$ its eigenvalue then $A^r v = \lambda^r v$ for all real $r>0$ .

linear-algebra matrices

modified 1 hour ago xpaul 28.2k

0

votes

0

answers

18

views

By considering the following tent map, we need to find the fixed points of the system; define their stability, and draw the cobweb diagram.

dynamical-systems fixed-point-theorems fixed-points

asked 1 hour ago Kate G 1

1

vote

0

answers

18

views

Finding an unknown PDF and an unknown function, given a relationship between the two and some constraints.

ordinary-differential-equations functions probability-distributions systems-of-equations nash-equilibrium

modified 1 hour ago B Chong 11

1

vote

1

answer

13

views

Creating a graph within specific vertex/degree parameters

graph-theory

answered 1 hour ago Brian M. Scott 510k

1

vote

0

answers

26

views

Linear transformation with an integral.

linear-algebra integration linear-transformations

modified 2 hours ago Alonso Delfín 5,068

2

votes

0

answers

54

views

Exterior Algebra as Universal Enveloping Algebra?

abstract-algebra lie-algebras exterior-algebra symmetric-algebra

modified 2 hours ago M.C. 384

1

vote

1

answer

19

views

How to show from the definition of topological space that the topology $\tau$ is the family of open sets of a topology with a filter base?

general-topology proof-explanation

answered 2 hours ago Brian M. Scott 510k

1

vote

2

answers

49

views

Can someone explain to me in easier terms how to calculate if a 3d point in space is intersecting a plane.

vectors 3d

modified 2 hours ago None 116

1

vote

1

answer

31

views

Prove that if $x$ is the greatest lower bound of $U$, then $x$ is the least upper bound of $B$

proof-verification elementary-set-theory

answered 2 hours ago Timmy Chyrklund 81

1

vote

0

answers

14

views

Graph as a function itself?

real-analysis functions

asked 2 hours ago DerivativesGuy 433

0

votes

0

answers

10

views

On copositivity criteria

linear-algebra matrices copositivity

modified 2 hours ago Anthony Saint-Criq 566

0

votes

0

answers

17

views

Output when a line capacity is stretched.

probability statistics

modified 2 hours ago Paralyzed_by_Time 465

0

votes

0

answers

27

views

Stuck on Classical intro to Modern Number Theory page 157?

number-theory field-theory finite-fields

asked 2 hours ago James 85

0

votes

0

answers

6

views

Degenerate simplex is the degeneracy of a unique non-degenerate simplex

category-theory solution-verification simplicial-stuff

asked 2 hours ago jgon 24.5k

3

votes

0

answers

20

views

Point compactification of $\mathbb{R}^2$ into $\mathbb{S}^2$

spherical-coordinates conformal-geometry compactification

asked 2 hours ago Syr 558

0

votes

0

answers

17

views

Homology of $S^n-K$ is acyclic, where $K$ is union of 2 disks

algebraic-topology homology-cohomology homological-algebra

modified 2 hours ago Pink Panther 726

3

votes

1

answer

33

views

Let $E_1 \subset E_2$ both be compact and $m(E_1) = a, m(E_2) = b$. Prove there exists a compact set $E$ st $m(E) = c$ where $a < c < b$.

real-analysis measure-theory measurable-sets

modified 2 hours ago Umberto P. 44.5k

2

votes

1

answer

26

views

Understanding lemma regarding fundamental class

algebraic-number-theory group-cohomology class-field-theory galois-cohomology

answered 2 hours ago anon 1

0

votes

0

answers

13

views

Taft-Hopf Algebra has dimension $N^2$?

linear-algebra abstract-algebra finitely-generated hopf-algebras hamel-basis

asked 2 hours ago M.C. 384

1

vote

0

answers

13

views

What's wrong in this derivation of backpropagation errors?

calculus matrices matrix-calculus neural-networks

asked 2 hours ago Dan Goldwater 149

1

vote

0

answers

20

views

Different Representation of a Direct Product

computational-mathematics gap

modified 2 hours ago Alexander Konovalov 5,803

34

votes

0

answers

530

views

An illusionist and his assistant are about to perform the following magic trick.

combinatorics graph-theory contest-math puzzle matching-theory

modified 2 hours ago Aqua 73.2k

2

votes

0

answers

31

views

Lower-bound on $\|\mathbb E [X/\|X\|]\|$ given a random vector $X$ on $\mathbb R^m$ veryfing $\|X\| \ge c$ a.s

probability probability-theory statistics concentration-of-measure

modified 2 hours ago dohmatob 5,657

0

votes

0

answers

16

views

Find a formula for the current after $t$ seconds, given that the voltage is initially $0$, and a constant current of value $k$ is applied.

calculus integration

modified 2 hours ago Anton Vrdoljak 1,711

0

votes

0

answers

12

views

Probability of Being One of Multiple Selected

probability

modified 2 hours ago Timothy Horton 1

2

votes

0

answers

14

views

“Being an algebraic space” is local property on the target

algebraic-geometry category-theory

asked 2 hours ago zom 103

2

votes

1

answer

51

views

Do the link cobordism induced maps on Khovanov homology for different diagrams commute?

low-dimensional-topology

modified 3 hours ago GageMartin 101

-1

votes

1

answer

18

views

Find CDF of $aX+bY$; Given that $X \sim \text{Lognormal}(\mu_1,\sigma_1^2)$ and $Y \sim\text{Lognormal}(\mu_2,\sigma_2^2)$

probability statistics probability-distributions

modified 3 hours ago Kenta S 3,875

1

vote

0

answers

19

views

Tangent concentric ellipses

geometry conic-sections

modified 3 hours ago Jyrki Lahtonen 117k

1

vote

1

answer

12

views

Separability of a $\sigma$-algebra generated by an algebra

real-analysis measure-theory

modified 3 hours ago Kenta S 3,875

2

votes

0

answers

21

views

Computing the Galois Action of a Frobenius Morphism on Projective $\ell$-adic Cohomology Groups

number-theory algebraic-geometry projective-space group-cohomology zeta-functions

asked 3 hours ago chives 65

0

votes

0

answers

3

views

Formula for Stereographic Projection of Celestial Sphere centered at north point of horizon ,not at North Pole.

coordinate-systems stereographic-projections celestial-mechanics

asked 3 hours ago 건우이 1

1

vote

0

answers

18

views

Independence of asymptotic joint distribution of order statistic

probability probability-theory proof-explanation order-statistics extreme-value-theorem

modified 3 hours ago annie_lee 575

2

votes

0

answers

11

views

Why is Kantorovich optimal transport dual not smooth?

real-analysis probability functional-analysis derivatives optimization

asked 3 hours ago W. Volante 943

2

votes

0

answers

17

views

Complex K-theory cohomology ring $K^*(T^2)$

algebraic-topology k-theory

modified 4 hours ago Arctic Char 2,533

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