Mathematics Stack Exchange

1

vote

2

answers

12

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Matrices in $O(n) \setminus SO(n)$

orthogonal-matrices reflection

modified 55 secs ago Federico Fallucca 2,122

0

votes

0

answers

8

views

Proof of $ \sqrt{2}|z|\geq|Re(z)| + |Im(z)|$

complex-analysis

modified 56 secs ago Kenneth 5

0

votes

0

answers

2

views

Distribution of product of two binomial coefficients

combinatorics probability-distributions binomial-distribution

asked 1 min ago EmFed 1

0

votes

2

answers

21

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About Conditional Variance $X$ Has distribution $ U(0,1)$ and $Y$ has distribution $ U(0,X)$

probability probability-distributions random-variables variance

modified 1 min ago drhab 102k

0

votes

2

answers

11

views

calculation of $\int^{1}_{0}\frac{1}{\sqrt{x-x^2}(x^2+3x+2)}dx$

definite-integrals

answered 3 mins ago Robert Z 98.5k

0

votes

1

answer

24

views

Wheel of Fortune - Optimal Stopping Time

stochastic-processes

modified 3 mins ago Minus One-Twelfth 1,318

0

votes

0

answers

28

views

Infinite tensor product identity

measure-theory hilbert-spaces tensor-products

modified 4 mins ago lionelbrits 166

0

votes

1

answer

28

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Describe closure and interior of subspace $A$ of $X \times B$ in terms of interior and closure of his projection in $X$

general-topology

modified 7 mins ago William Elliot 8,267

2

votes

0

answers

57

views

Consider $F(a)=\int_{0}^{+\infty}{\frac{1}{1+x^a(\ln(1+x)^2f(x)}} \, \mathrm{d}x$

real-analysis functional-analysis

modified 8 mins ago LiTaichi 128

0

votes

1

answer

759

views

How to compute SSR with just residuals and Xi?

statistics sums-of-squares

modified 9 mins ago Community♦ 1

0

votes

0

answers

11

views

Conditional Probability on set of random variables: is on order needed?

probability set-theory conditional-probability

modified 12 mins ago Valentin Iovene 139

4

votes

2

answers

96

views

Computing the index $\left(\mathbb Z\left[\frac{1+\sqrt{5}}{2}\right]:\mathbb Z \left[\sqrt{5}\right]\right)$?

abstract-algebra algebraic-number-theory quotient-group

answered 18 mins ago nguyen quang do 8,929

4

votes

1

answer

75

views

Determine all integers $i$ such that $(i-29)(i+29)$ is a square number

elementary-number-theory square-numbers

modified 18 mins ago greedoid 43.8k

0

votes

0

answers

4

views

Quotients by commuting equivalence relations

equivalence-relations

asked 18 mins ago Arrow 5,214

0

votes

0

answers

26

views

Is $M=\frac{\mathbb{Z}^3}{\langle (3,3,1),(2,2,2)\rangle}$ free?

abstract-algebra ring-theory modules quotient-spaces free-modules

modified 19 mins ago user26857 39.3k

1

vote

0

answers

29

views

Define a Borel function on the whole space with some constraints

measure-theory set-theory descriptive-set-theory measurable-functions polish-spaces

modified 20 mins ago LBJFS 257

0

votes

0

answers

7

views

Unicode notation of Euler Constant

notation eulers-constant

asked 22 mins ago GNUSupporter 8964民主女神地下教會 13.3k

1

vote

1

answer

15

views

Prove that there exists a $k$ such that the sequence obtained by listing each element of $S$ a total $k$ times is a degree sequence of some graph.

combinatorics graph-theory

modified 23 mins ago greedoid 43.8k

0

votes

0

answers

5

views

Homotopic Equivalence of the set of all continous maps from X to $R^n$

abstract-algebra general-topology algebraic-topology differential-topology geometric-topology

asked 24 mins ago DatSci13 11

0

votes

1

answer

20

views

A problem on multi-variable calculus

ordinary-differential-equations multivariable-calculus

answered 28 mins ago GReyes 1,535

0

votes

0

answers

7

views

Confusion in derivation of “Clairaut's theorem on equality of mixed partials”

calculus limits derivatives proof-explanation partial-derivative

asked 29 mins ago Joe 292

0

votes

0

answers

7

views

A property of a singular increasing function on [a, b]

real-analysis

asked 30 mins ago Jerry.Li 1

1

vote

1

answer

25

views

Roots of equation with complex numbers

complex-numbers roots

answered 33 mins ago Hyperion 631

0

votes

0

answers

9

views

Grouping dependant variables

finite-fields cryptography

modified 36 mins ago Yuon 8

0

votes

0

answers

7

views

How long is the subset list in general?

combinatorics

asked 42 mins ago user120911 231

4

votes

2

answers

64

views

Can this puzzle be solved mathematically?

discrete-mathematics logic puzzle

answered 46 mins ago greedoid 43.8k

-1

votes

1

answer

18

views

Probability that the student knows correct answer

probability

answered 48 mins ago drhab 102k

3

votes

1

answer

110

views

Question about a result on odd perfect numbers

elementary-number-theory conjectures divisor-sum perfect-numbers

answered 53 mins ago Jose Arnaldo Bebita Dris 5,453

1

vote

1

answer

67

views

Want to prove certain sum representation of $\cot(x)$

complex-analysis fourier-series harmonic-analysis

answered 55 mins ago robjohn♦ 268k

0

votes

1

answer

23

views

possible number of sheets for a Moebius band covering

algebraic-topology covering-spaces mobius-band

modified 56 mins ago William 2,235

-3

votes

0

answers

34

views

I'm having problem solving this triple integral problem, please help

complex-integration

modified 57 mins ago TechDroid 1

0

votes

1

answer

13

views

The expression “independent” in the context of Analytical Mechanics

linear-algebra classical-mechanics

answered 58 mins ago GReyes 1,535

3

votes

1

answer

68

views

Linear Least-Squares Problem with Inequality Constraints on Residual

linear-algebra optimization numerical-linear-algebra least-squares numerical-optimization

modified 58 mins ago Alex Shtof 379

-2

votes

1

answer

16

views

Getting an Angle on arc

geometry circle angle

modified 58 mins ago GNUSupporter 8964民主女神地下教會 13.3k

0

votes

0

answers

20

views

When the slope is flipping

calculus derivatives smooth-functions

asked 59 mins ago gar 1

0

votes

3

answers

30

views

Absolute value of complex exponential divided by complex number

integration complex-numbers exponential-function

modified 1 hour ago user36610 3

4

votes

1

answer

40

views

Why does $G$ need to be finite in this proof of a normal subgroup $N$ containing all elements of order coprime to $[G:N]$?

abstract-algebra group-theory

modified 1 hour ago Shaun 9,268

-2

votes

1

answer

22

views

How to find subsets' intersection

combinatorics

modified 1 hour ago Tomislav Ostojich 657

3

votes

0

answers

32

views

Sustainable population - When to breed

real-analysis systems-of-equations bounded-variation

modified 1 hour ago Frank Hubeny 420

0

votes

0

answers

29

views

Perimeter of a parallelogram just with the area

geometry euclidean-geometry area

modified 1 hour ago Anirban Niloy 487

0

votes

0

answers

29

views

Simplify formula by removing sum from it

summation

modified 1 hour ago Donvino 101

4

votes

3

answers

112

views

Minimum number of steps in water measure problem

combinatorics puzzle

answered 1 hour ago Oleg567 13.9k

0

votes

0

answers

7

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The y axis is the directrix of an ellipse with e=1/2 and the correspondinf focus is (3,0).find the equation of it's auxiliary circle.

conic-sections

asked 1 hour ago Kakan Mukherjee 1

0

votes

1

answer

18

views

Minimal dimension of an affine space in $\mathbb R^n$ that could divide an open set $U$ into disconnected components?

linear-algebra general-topology connectedness

answered 1 hour ago jmerry 9,981

1

vote

0

answers

72

views

Area of semialgebraic set

integration analysis polynomials area semialgebraic-geometry

modified 1 hour ago Rodrigo de Azevedo 13k

0

votes

0

answers

41

views

Computational complexity of a feasibility LP with $m$ inequalities, in $d$ dimension?

linear-programming computational-complexity decision-problems

modified 1 hour ago Rodrigo de Azevedo 13k

1

vote

0

answers

16

views

Metrics on functions that use both the domain and range's metric.

geometry functional-analysis metric-spaces

modified 1 hour ago PyRulez 4,941

4

votes

1

answer

62

views

+50

Application of Schwarz lemma and Liouville's theorem

complex-analysis

modified 1 hour ago Chinnapparaj R 5,492

0

votes

0

answers

25

views

What is the Hessian of $(\min(0, A) ) ^ 2$

matrices matrix-calculus hessian-matrix

modified 1 hour ago MysteryGuy 338

2

votes

0

answers

59

views

A rigorous yet intuitive summary of inflection and critical points for beginning calculus?

calculus general-topology derivatives proof-verification optimization

modified 1 hour ago Mitjackson 51

0

votes

0

answers

20

views

Second-order ODE recurrence relation

sequences-and-series ordinary-differential-equations recurrence-relations frobenius-method

asked 1 hour ago user583893 28

0

votes

0

answers

26

views

Is there a cleverer way to find the largest Sidon set in {1,…,N}?

combinatorics

modified 1 hour ago Asaf Karagila♦ 305k

1

vote

0

answers

17

views

Finitely Additive Homogeneous Translation Invariant Measure on $\mathcal{P}(\mathbb{R})$

real-analysis functional-analysis measure-theory hahn-banach-theorem

modified 1 hour ago pitariver 454

4

votes

0

answers

38

views

Let $S=\{p(x) \in \mathbb Z[X] :|p(x)| \leq 2^x, \forall x\in \mathbb N\}$. Find $|S|$.

real-analysis analysis polynomials

modified 1 hour ago YuiTo Cheng 1,766

4

votes

1

answer

20

views

Conditional running maximum of Geometric Brownian Motion (maximum of Brownian Bridge)

probability probability-distributions brownian-motion conditional-probability

modified 1 hour ago saz 81k

3

votes

1

answer

53

views

Does the specific condition on a normal subgroup of a finite group imply that it is a direct factor?

abstract-algebra group-theory finite-groups universal-algebra direct-product

modified 1 hour ago Keith Kearnes 5,694

1

vote

1

answer

21

views

Prove: If $p=p^+e_1$ and $q=q^+e_2$, then the relative error…

proof-verification numerical-methods

answered 2 hours ago Claude Leibovici 122k

0

votes

0

answers

14

views

Probability of a point taken from a certain normal distribution will be greater than other points taken from other normal distributions?

probability normal-distribution

asked 2 hours ago Jakub Bielan 4

2

votes

2

answers

36

views

How to prove B from a premise in which B does not occur using natural deduction?

logic natural-deduction

modified 2 hours ago Frank Hubeny 420

-1

votes

0

answers

23

views

Computing the area of a given surface in a Cartesian coordinate system

integration multivariable-calculus vectors vector-analysis

modified 2 hours ago Mauve 1,548

3

votes

1

answer

18

views

Opposite category of SET is Boolean Algebra

category-theory boolean-algebra

answered 2 hours ago Kevin Carlson 33.2k

0

votes

1

answer

21

views

Are there applications of equivalent matrices?

matrices applications

answered 2 hours ago Ivo Terek 46.3k

0

votes

0

answers

18

views

for each point on the curve, the line segment of the tangent line from tahe curve point to the $y-$ axis has length 1.

differential-geometry vector-analysis parametrization

asked 2 hours ago Math geek 383

1

vote

0

answers

8

views

Newton polynomial divided differences

numerical-methods

asked 2 hours ago Jimmy Sabater 2,719

0

votes

1

answer

29

views

Does the following Infinite product converge to anything?

real-numbers infinite-product

answered 2 hours ago Claude Leibovici 122k

1

vote

0

answers

13

views

some examples of a Banach algebra with given conditions

reference-request examples-counterexamples banach-algebras

asked 2 hours ago Fermat 4,415

1

vote

1

answer

31

views

Let $C$ be the cubic curve $ y^2 = x^3 + ax^2 + bx + c $ with singular point $S$. Show that $S$ must have rational coordinates.

algebra-precalculus elliptic-curves

modified 2 hours ago Lord Shark the Unknown 105k

0

votes

0

answers

35

views

Graphs with rational eigenvalues

graph-theory eigenvalues-eigenvectors spectral-graph-theory adjacency-matrix

modified 2 hours ago Amin 1,341

1

vote

4

answers

178

views

Does $\sum_{n=1}^{\infty}\sin\left(\frac1{\sqrt{n}}\right)$ converge?

sequences-and-series convergence

modified 2 hours ago Martin Sleziak 44.7k

3

votes

2

answers

70

views

Provide example of two series that both diverge but $\sum\min\{a_n,b_n\}$ converges

real-analysis sequences-and-series convergence examples-counterexamples

modified 2 hours ago Martin Sleziak 44.7k

0

votes

0

answers

15

views

Continously differentiable function in a arbitrary set

calculus pde

asked 3 hours ago dmtri 1,508

5

votes

0

answers

80

views

+50

A more natural solution to finding the general terms of a recurrence relation in $2$ variables

algebra-precalculus recurrence-relations contest-math alternative-proof

modified 3 hours ago YuiTo Cheng 1,766

0

votes

1

answer

17

views

Derivatives, chain rules, and inverse functions

chain-rule

answered 3 hours ago Haris Gusic 1,202

0

votes

2

answers

99

views

An algorithm to decide whether a polyhedron is a subset of another polyhedron

algorithms linear-programming duality-theorems polyhedra decision-problems

modified 3 hours ago Rodrigo de Azevedo 13k

0

votes

0

answers

35

views

if $z\in \mathbb{C}$ , then $\bar{z} \in \mathbb{Q}(z)$ [finding $x^3 + bx + c$ splitting field degree]

abstract-algebra field-theory

modified 3 hours ago dan 573

5

votes

1

answer

96

views

+50

Sobolev embedding for the $L^q$ norm.

real-analysis pde sobolev-spaces regularity-theory-of-pdes fractional-sobolev-spaces

modified 3 hours ago timur 12k

0

votes

0

answers

11

views

Lack-of-fit SS Question

linear-regression

modified 3 hours ago user647548 1

1

vote

0

answers

11

views

Intrinsic vs. extrinsic surface curvature

differential-geometry metric-spaces

modified 3 hours ago safesphere 328

2

votes

1

answer

66

views

Fitch-style Deductive Proof

logic propositional-calculus proof-theory natural-deduction formal-proofs

answered 3 hours ago Frank Hubeny 420

0

votes

0

answers

15

views

How to prove the finiteness of lower semi-continuous function?

real-analysis optimization convex-analysis

asked 3 hours ago Ze-Nan Li 28

1

vote

0

answers

13

views

Find critical points and inflection points given the derivative

calculus general-topology derivatives proof-verification optimization

asked 3 hours ago Mitjackson 51

1

vote

0

answers

10

views

Number of right jumps of random walk (with possibility of inaction) before hitting time

probability-theory stochastic-processes random-walk

asked 4 hours ago Cristian 61

3

votes

1

answer

20

views

One Dimensional Wave Equation with Piecewise Initial Conditions

pde wave-equation initial-value-problems

answered 4 hours ago Dylan 13.1k

0

votes

0

answers

14

views

Greatest volume of sphere inscribed in a cone with given Lateral area

derivatives volume maxima-minima

modified 4 hours ago Umesh shankar 2,722

0

votes

0

answers

26

views

continuous but non-differentiable function having countable points of non-differentiablity

real-analysis

modified 4 hours ago mate89 181

0

votes

0

answers

5

views

Trying to generate two equations that describe debt growth from numerous samples

approximation regression

modified 4 hours ago Stoutcat 1

4

votes

1

answer

46

views

Show that all normals to $\gamma(t)=(\cos(t)+t\sin(t),\sin(t)-t\cos(t))$ are the same distance from the origin.

differential-geometry

modified 4 hours ago coreyman317 774

1

vote

2

answers

42

views

Show that the free group on three generators is a subgroup of the free group on two generators

group-theory algebraic-topology free-groups

modified 4 hours ago Connor Malin 115

0

votes

0

answers

12

views

Determine transformation of parent graph given new graph and 2 ordered pairs

linear-algebra algebra-precalculus

asked 4 hours ago user163862 870

0

votes

0

answers

7

views

What is champe's change / champe change swaps, fanning in graph theory?

graph-theory

asked 4 hours ago Peeyush Kushwaha 408

6

votes

0

answers

90

views

+100

Corollary of the Malgrange Preparation Theorem

real-analysis analysis modules dynamical-systems germs

modified 5 hours ago Matheus Manzatto 1,325

4

votes

0

answers

30

views

How to tell whether function $x^a \mod{b}$ is bijective or not?

elementary-number-theory functions modular-arithmetic

modified 5 hours ago Alan Muniz 2,206

1

vote

0

answers

15

views

Largest eigenvalue of a graph is non-decreasing

linear-algebra algebraic-graph-theory

modified 5 hours ago DesmondMiles 99

2

votes

0

answers

11

views

What is the smallest poset with automorphism group $C_n$?

finite-groups order-theory automorphism-group

asked 6 hours ago h4tter 33

4

votes

1

answer

162

views

What does it mean geometrically for a graded ring to be generated in degree $1$?

algebraic-geometry

modified 6 hours ago loch 2,043

0

votes

1

answer

15

views

Trying to understand a proof where disjoint decomposition of $\mathbb R^n$ is used.

real-analysis general-topology

answered 6 hours ago Mriganka Basu Roy Chowdhury 311

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