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3

votes

3

answers

34

views

Difference between hypotenuse and larger leg in a Pythagorean triple

number-theory conjectures pythagorean-triples

modified 3 mins ago John Omielan 36.8k

1

vote

0

answers

37

views

If there is a sequence $x_n \to \infty$ such that $\lim_{n \to \infty} \int_0^{x_n} f(x)dx$ converges, does $\int_0^{\infty} f(x)dx$ converge?

real-analysis integration solution-verification improper-integrals

modified 6 mins ago kimchi lover 21.6k

6

votes

2

answers

175

views

Computing $\sum_{k=1}^{\infty}\frac{1}{k}\int_{\pi k}^{\infty}\frac{\sin(x)}{x}dx$

real-analysis sequences-and-series

answered 8 mins ago aaaaaaaaabbbbbbbbbcccccc 111

4

votes

3

answers

43

views

In a ring with identity, $a$, $b$, $c$ are such that $ab=ba=1$ and $ac=0$. Show that $c=0$.

abstract-algebra ring-theory

modified 2 mins ago Bill Dubuque 249k

0

votes

1

answer

15

views

Calculating quartiles of a given PDF

statistics percentile

answered 12 mins ago LogLogLogLogx 113

1

vote

0

answers

9

views

To check differentiability of $f(z)=z |z|$ at $(0,0).$

complex-analysis derivatives

modified 24 secs ago Thomas Andrews 153k

0

votes

0

answers

4

views

Calculating probability form closed form function?

probability probability-distributions

asked 13 mins ago Parikshit Pareek 95

0

votes

2

answers

20

views

To test differentiability of the function $f(z)=z \operatorname{Re}z$ at $(0,0)$

complex-analysis derivatives

answered 14 mins ago peek-a-boo 23.8k

0

votes

0

answers

25

views

+50

Problem 5.21 in Boyd's Convex Optimization about strong duality failing

calculus convex-optimization

modified 15 mins ago Pedro 5,627

0

votes

2

answers

29

views

Location roots for a special class of polynomials in $\mathbb{Z}[X]$

polynomials

answered 16 mins ago Paul Sinclair 33.4k

3

votes

1

answer

40

views

$E[X_T]$ for $T=\min\{n: \sum_{i=1}^nX_i\geq1\}$ where $X_i\sim U[0,1]$.

probability probability-theory expected-value

modified 21 mins ago md5 1,758

0

votes

0

answers

13

views

I roll seven identical six-sided dice simultaneously. How many different outcomes are possible?

probability

asked 24 mins ago kevin forrestal 1

0

votes

0

answers

33

views

Find $\sum_{n=1}^{\infty} e^{-(\frac{n\pi}{a})^2}$

integration sequences-and-series complex-analysis summation contour-integration

modified 26 mins ago Henry Lee 9,688

0

votes

1

answer

11

views

Determine values of a and b such that f(x) is continuous at x = 1.

calculus limits limits-without-lhopital

answered 30 mins ago Lion Heart 2,915

0

votes

1

answer

2k

views

Work to empty an inverted pyramid

calculus

modified 32 mins ago Community♦ 1

0

votes

0

answers

13

views

Describe basis for following topology

general-topology

asked 33 mins ago Plotinus 85

0

votes

1

answer

36

views

Second order Differ. Eq.

ordinary-differential-equations

modified 33 mins ago Henry Lee 9,688

0

votes

0

answers

36

views

How to count the divisors not exceeding $\log ^2N$ of a given number $N$ in asymptotics?

number-theory prime-numbers algorithms

modified 37 mins ago Wenling Liu 1

1

vote

1

answer

50

views

Why no line graph has -2 as a main eigenvalue?

graph-theory algebraic-graph-theory

modified 59 mins ago RobPratt 24.7k

3

votes

1

answer

30

views

How many 5 card hands out of a 52 card deck are there that have at least one red card.

combinatorics card-games

modified 1 hour ago RobPratt 24.7k

0

votes

0

answers

7

views

A $n$ variables inequality with sine function

inequality contest-math lagrange-multiplier

asked 1 hour ago Modern_Hunter 39

10

votes

0

answers

196

views

Is there any “nice” representation for algebraic numbers of degree 3 (or higher)?

abstract-algebra number-theory continued-fractions

modified 1 hour ago Chris Brooks 6,765

2

votes

1

answer

16

views

Bound on difference between side lengths of a right triangle whose sides are pairwise coprime

triangles

modified 1 hour ago Calvin Lin 56.8k

0

votes

0

answers

11

views

Fast evaluation of trace of inverse matrix quadratic form

matrix-equations matrix-decomposition trace pseudoinverse

modified 1 hour ago JDoe2 457

10

votes

0

answers

279

views

+100

Exercise 1.24 from Joe Harris' Algebraic Geometry: First Course

algebraic-geometry curves schemes algebraic-curves projective-schemes

modified 1 hour ago Isak the XI 701

0

votes

1

answer

1k

views

Computational efficiency using Gaussian elimination

matrices numerical-methods computational-complexity gaussian-elimination

modified 1 hour ago RobPratt 24.7k

0

votes

0

answers

29

views

Binomial Coefficients Identity (unsure if this is true)

combinatorics summation binomial-coefficients

modified 1 hour ago RobPratt 24.7k

0

votes

0

answers

12

views

Every free group admits a fixed-point-free involution automorphism

group-theory free-groups combinatorial-group-theory fixed-points involutions

asked 1 hour ago Gauss 1,248

1

vote

0

answers

23

views

Need help understanding an answer - condition when $E(Y-\lfloor Y \rfloor)$ is uniform

probability central-limit-theorem

modified 1 hour ago Rohit Pandey 4,364

-1

votes

0

answers

5

views

The vector field F(x,y,z) = (x+1)i − (2y+1)j + zk is given. c (1, 0, 0), (0, 1, 0), (0,0,1) are the clockwise border of the triangle with the crest

integration

asked 1 hour ago cando 1

2

votes

1

answer

24

views

Calculate the following Limit $\lim_{n\rightarrow \infty} \sqrt{n}\int_{0}^{\infty} \frac{1-\cos(x)}{1+nx^6}dx$

real-analysis limits lebesgue-integral

modified 1 hour ago Olivier Oloa 117k

0

votes

1

answer

41

views

Let $A$,$B$, and $C$ be finite sets, show that: (a.) $|A^{c} \cap B|$ = $|B|$-$|A\cap B|$. It really confused me due to complement. Please help me.

combinatorics

answered 1 hour ago ConMan 10.2k

1

vote

0

answers

15

views

Question about Going down theorem in Gopalakrishnan

commutative-algebra galois-theory integral-extensions

asked 1 hour ago Lekha Das 11

-1

votes

1

answer

55

views

Passing Alternate Numbers of Coins Around a Table

solution-verification puzzle

modified 1 hour ago Josiah Ober 1

2

votes

0

answers

20

views

Is it possible to determine whether a random variable has density without first finding its density function?

real-analysis probability solution-verification density-function

modified 1 hour ago Leo 3,085

-1

votes

1

answer

44

views

Contest Sequence problem that seems to contradict itself in the question

sequences-and-series algebra-precalculus recurrence-relations contest-math

answered 1 hour ago Calvin Lin 56.8k

2

votes

0

answers

21

views

Hint for proving some meromorphic functions are rational

complex-analysis

modified 2 hours ago Masacroso 23.3k

1

vote

0

answers

36

views

State whether each of the integrals below is convergent or divergent and justify your answer.

real-analysis integration convergence-divergence solution-verification improper-integrals

modified 2 hours ago Andre 369

0

votes

0

answers

26

views

What does $||\nabla e^{t\Delta}w||_{L^p(\Omega)}$ mean?

functional-analysis partial-differential-equations notation terminology semigroup-of-operators

modified 2 hours ago Jose Avilez 2,339

1

vote

1

answer

14

views

Question regarding convergence in distribution

limits probability-theory convergence-divergence random-variables

modified 2 hours ago Bernard 302

0

votes

1

answer

18

views

Difference of Two Consecutive $n$th Powers

sequences-and-series

modified 2 hours ago Lion Heart 2,915

0

votes

1

answer

14

views

Why $adjacent = OP^2+OQ^2-PQ^2$ and $hypotenuse = 2OP\cdot OQ$?

geometry trigonometry

modified 2 hours ago Luke 40

0

votes

2

answers

57

views

Is Cohen's model of $\mathsf{ZF}+\neg \mathsf{C}$ transitive?

logic set-theory foundations

answered 2 hours ago Reveillark 11.5k

0

votes

0

answers

11

views

Nested function operator/notation?

functions notation

asked 2 hours ago Remeraze 23

0

votes

1

answer

7

views

Conditional expectation is $T$-invariant in a measure preserving system.

dynamical-systems conditional-expectation ergodic-theory

answered 2 hours ago Kavi Rama Murthy 267k

0

votes

0

answers

11

views

Draw a graph of an injective function, only given a domain

functions graphing-functions

asked 2 hours ago Uno Fish 1

1

vote

0

answers

24

views

Condition for measurable function for function with values in $[-\infty,\infty]$

real-analysis measure-theory solution-verification measurable-functions

modified 2 hours ago lorenzo 2,118

1

vote

1

answer

30

views

Bounding the distance to the mean given the sum of squares distances

geometry upper-lower-bounds triangle-inequality

modified 2 hours ago Tomer Wolberg 428

0

votes

1

answer

22

views

Points on two of the sides of a triangle

geometry euclidean-geometry triangles

modified 2 hours ago Lion Heart 2,915

4

votes

1

answer

105

views

+100

Where are the imaginary components in a moment generating function (MGF) of a distribution?

probability probability-distributions laplace-transform moment-generating-functions

modified 2 hours ago Math tourist 499

1

vote

1

answer

13

views

Need help in proving $\lambda \notin \sigma(M_f) \implies \lambda \notin \text {ess ran} f.$

measure-theory spectral-theory

answered 2 hours ago Reveillark 11.5k

0

votes

0

answers

19

views

Finding a closed-form for the sum $\sum_{n=1}^{\infty}\frac{\left(-1\right)^{n}H_{2n}}{n^{4}}$

sequences-and-series definite-integrals special-functions closed-form polylogarithm

asked 2 hours ago David H 25.9k

1

vote

1

answer

21

views

Integral of function depending on positive definite matrix

matrices definite-integrals

modified 2 hours ago NN2 5,998

0

votes

0

answers

7

views

Solve this Linear Programming Problem(LPP) using Graphical method:

linear-programming

asked 2 hours ago John 419

5

votes

2

answers

46

views

Possible corollary of Jordan's curve theorem

general-topology curves connectedness plane-geometry plane-curves

answered 2 hours ago Brandon du Preez 2,799

1

vote

0

answers

26

views

Angle formed by 3 points in the complex plane knowing their affixes

complex-numbers solution-verification

modified 2 hours ago Neox 373

2

votes

0

answers

21

views

Maximum number of comparisons required to define a partial ordering

order-theory

modified 3 hours ago NullSimplex 101

4

votes

0

answers

16

views

Asymptotic behavior of recurrence $x_{n+1}=\mbox{Stdev}(x_1,\dots,x_n)$

sequences-and-series statistics asymptotics recurrence-relations

asked 3 hours ago Vincent Granville 3,225

1

vote

0

answers

73

views

The basics of counting monic poynomials in $\mathbb{F}_p[\mathrm{x}]$.

abstract-algebra polynomials

modified 3 hours ago user26857 45.1k

2

votes

1

answer

50

views

Difference between using max function over functions and over values

functions

modified 3 hours ago ball_jan 47

2

votes

1

answer

59

views

Area under 1-x! over the unit interval. This is a modified equivalent representation of the area: inverse gamma function simply reflected about y=x.

integration inverse factorial gamma-function inverse-function

modified 3 hours ago Tyma Gaidash 1,053

0

votes

0

answers

19

views

What are the connections between versors and gyrovectors?

rotations hyperbolic-geometry noneuclidean-geometry

asked 3 hours ago Parad0xD9 1

0

votes

0

answers

44

views

What lessons can one draw from studying a concrete implementation of ZFC?

soft-question set-theory foundations learning

modified 3 hours ago Alex 21

1

vote

2

answers

17

views

figuring out the number of contestants that took part in the primary qualifications

combinatorics

modified 3 hours ago Jean Marie 57.7k

0

votes

1

answer

21

views

Proving the norm of multiplication operator is the infinity norm of the multiplier

functional-analysis operator-theory

answered 3 hours ago Alan 11.2k

3

votes

1

answer

64

views

Is this proof all right?

elementary-number-theory solution-verification induction

modified 3 hours ago Hanny Boy 143

0

votes

0

answers

15

views

Why QR iterations converges?

eigenvalues-eigenvectors numerical-linear-algebra

asked 3 hours ago Fakher Mokadem 101

5

votes

1

answer

62

views

proof that a countable union of countable sets is countable, why is $\sf ZF$ not enough?

elementary-set-theory axiom-of-choice

modified 3 hours ago Ynir 51

1

vote

1

answer

134

views

Question concerning Schwarz-Christoffel Mappings and Conformal Modulus

complex-analysis conformal-geometry quasiconformal-maps

answered 3 hours ago Lucas Oliveira 21

1

vote

1

answer

15

views

On properties of symmetric operators on Hilbert spaces

operator-theory hilbert-spaces unbounded-operators

answered 3 hours ago paul garrett 40.4k

2

votes

3

answers

41

views

Determine the sequence of functions $f_n(x)=nx^2e^{-nx}$ is uniformly convergent or not.

real-analysis uniform-convergence

modified 3 hours ago robjohn♦ 314k

1

vote

1

answer

27

views

Show union of local basis is a basis for topology (X, $\tau$)

general-topology proof-explanation

answered 3 hours ago Henno Brandsma 204k

0

votes

0

answers

30

views

If we know about the divisors of $n$, what can we comment about the divisors of $n+x$?

number-theory elementary-number-theory algebraic-number-theory divisor-sum divisor-counting-function

asked 3 hours ago Sayan Dutta 1,029

1

vote

1

answer

26

views

Proving second-countable, normal topological space with $U \in \tau$ has a continuous function $f(x) \neq 0$ iff $x \in U$.

general-topology

answered 3 hours ago Henno Brandsma 204k

1

vote

0

answers

13

views

Alternative proofs to integral test that $\large{\lim_{n\to\infty}\left(\sum_{j=1}^n \alpha^{\left(j^p\right)}\right)}$ converges; $0<\alpha,p<1.$

real-analysis sequences-and-series limits convergence-divergence alternative-proof

asked 3 hours ago Adam Rubinson 6,812

4

votes

0

answers

249

views

How to evaluate $\int_{1}^{\infty} \frac{\ln (v-1) \text{li} \left(v^2\right)}{v^5} \, dv$?

calculus integration improper-integrals special-functions closed-form

modified 3 hours ago KStarGamer 563

1

vote

0

answers

36

views

Doubt about the right way to write an $2-$form

differential-geometry tensor-products multilinear-algebra dual-spaces

modified 3 hours ago M.N.Raia 543

0

votes

0

answers

9

views

Back-projecting image point with 3x4 projection matrix to find world point

linear-algebra matrices projective-geometry

asked 4 hours ago David 1

-1

votes

0

answers

9

views

How to calculate bound of a time series?

inequality systems-of-equations upper-lower-bounds

asked 4 hours ago kaki no 1

1

vote

1

answer

28

views

Lambda calculus defining terms according to description

lambda-calculus

answered 4 hours ago md2perpe 19.3k

3

votes

0

answers

69

views

About convolution, how to finish the proof

complex-analysis lp-spaces convolution

modified 4 hours ago Maths1999_ 830

0

votes

0

answers

15

views

Help computing a complex integral along a curve using the definition

complex-analysis complex-integration parametrization

modified 4 hours ago cos_dm_math21 1,020

1

vote

0

answers

44

views

$Y^TX(X^TX+ \lambda I)^{-1}X^TY$

linear-algebra functional-analysis matrix-decomposition linear-regression

modified 4 hours ago rostader 187

3

votes

0

answers

53

views

Does measurability on product space implies strong measurability?

real-analysis integration functional-analysis measure-theory bochner-spaces

modified 4 hours ago celebi 1

-3

votes

1

answer

75

views

Having a hard time proving this limit

limits asymptotics quadratics

modified 4 hours ago Paul Sinclair 33.4k

2

votes

1

answer

32

views

Find the integral on this curve. (Vector field containing one point that is problematic).

integration curves vector-fields parametrization

answered 4 hours ago Math Lover 27.6k

0

votes

0

answers

8

views

Over a field of characteristic $p>0,$ do all non-separable morphisms have degree divisible by $p$?

finite-fields elliptic-curves algebraic-curves

asked 4 hours ago José 849

4

votes

0

answers

53

views

Is it possible to come up with a formula for upper bound for this?

number-theory prime-numbers prime-gaps sieve-theory

modified 5 hours ago Mr Green Gold 275

7

votes

2

answers

75

views

Sufficient condition for irreducibility of homogeneous polynomial (Exercise I. 5.9 in Hartshorne)

algebraic-geometry solution-verification irreducible-polynomials

modified 5 hours ago cos_dm_math21 1,020

4

votes

1

answer

27

views

Normal planes and spherical curves

analysis differential-geometry curves frenet-frame

answered 5 hours ago Ted Shifrin 93.5k

0

votes

0

answers

7

views

Fourier series- proving that the limit is zero

fourier-series dirichlet-convolution fejer-kernel

asked 5 hours ago user726608 722

0

votes

0

answers

8

views

Bivariate Gaussian Independence

probability stochastic-processes

asked 5 hours ago Jason Butler 169

3

votes

0

answers

22

views

Drawing the toric diagram for $\mathcal{L}^{m} \rightarrow T^{2}$ geometries.

algebraic-geometry mathematical-physics symplectic-geometry divisors-algebraic-geometry toric-geometry

modified 5 hours ago Ramiro Hum-Sah 144

0

votes

0

answers

5

views

Peripheralization of Conditional Distributions of head to tail model

probability conditional-probability bayesian-network marginal-probability

asked 6 hours ago pie 101

3

votes

0

answers

32

views

Fejer Kernel, showing that a given series is an approximate identity

real-analysis fourier-analysis fourier-series fejer-kernel

modified 6 hours ago Usermat 700

0

votes

1

answer

39

views

Is $\mathbb Z _p$ flat $\mathbb Z$-module?

abstract-algebra modules flatness

modified 6 hours ago user26857 45.1k

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