Mathematics Stack Exchange

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If $S_1=0$ and $S_2=0$ represent two non intersecting circles, what does $S_1+\lambda S_2=0$ represent?

geometry euclidean-geometry analytic-geometry circles

modified 3 mins ago Light Yagami 3,305

1

vote

1

answer

12

views

When I build a representative matrix, I don't understand when to “transpose” its components

linear-algebra matrices transformation transpose

answered 3 mins ago Azur 1,042

0

votes

0

answers

2

views

Flatness of $k[x]$ over $k[s,t]$, where $s$ is even and $k$ is odd

ring-theory commutative-algebra flatness

asked 3 mins ago user237522 5,285

1

vote

0

answers

6

views

Does every edge has at least one outgoing edge implies the graph contains a cycle?

graph-theory

asked 6 mins ago error404 11

1

vote

1

answer

17

views

“Sliding window” permutations

matrices permutations

modified 7 mins ago Phil Huang 11

1

vote

0

answers

9

views

Euler product over a finite subset of composite numbers

analytic-number-theory

asked 11 mins ago Soham 1,515

1

vote

0

answers

4

views

The proof of a property of mirror descent

real-analysis convex-analysis convex-optimization gradient-descent

asked 15 mins ago Wheel 175

2

votes

0

answers

12

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Every bounded linear operator is compact

functional-analysis operator-theory operator-algebras compact-operators

asked 15 mins ago Anupam 119

0

votes

1

answer

18

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Uniqueness of simultaneous diagonalization via congruence

linear-algebra matrices diagonalization

modified 16 mins ago Rodrigo de Azevedo 17.2k

0

votes

1

answer

26

views

Does the square root function behave the same when calculating complex roots?

complex-numbers arithmetic roots radicals

answered 17 mins ago Obsessive Integer 101

1

vote

2

answers

18

views

Proofs involving the cardinality of the set of continuous functions

real-analysis proof-explanation

answered 17 mins ago Hagen von Eitzen 341k

1

vote

1

answer

13

views

Find the first two terms of the perturbation series solution to the IVP

ordinary-differential-equations partial-differential-equations perturbation-theory

answered 20 mins ago Lutz Lehmann 94.8k

0

votes

0

answers

15

views

Should one choose to study measure theory over probability theory?

probability measure-theory stochastic-processes

asked 22 mins ago CakesCakesCakes 29

2

votes

0

answers

775

views

Subgroups of given index of a finitely generated group

abstract-algebra group-theory finitely-generated

modified 23 mins ago Derek Holt 69.1k

-1

votes

0

answers

10

views

cardinality of units in a commutative ring of cardinality odd

abstract-algebra ring-theory

modified 24 mins ago anjali 55

0

votes

0

answers

5

views

Residues of Elliptic functions and non-isolated singularity

complex-analysis residue-calculus elliptic-functions

asked 26 mins ago Lelouch 365

0

votes

0

answers

14

views

There are 12 flowers, 9 yellow and 3 red. What is the probability picking 2 red flowers in two turns?

probability conditional-probability

asked 26 mins ago Oliver Semantics 1

1

vote

1

answer

13

views

Is this proof of the radius of convergence correct?

real-analysis solution-verification

answered 1 min ago Fred 71.3k

-1

votes

0

answers

13

views

Question from a book

probability probability-theory statistics probability-distributions probability-limit-theorems

asked 28 mins ago ron 1

1

vote

1

answer

12

views

Continuity of $g(t):=f(tx,ty)$

real-analysis analysis multivariable-calculus derivatives continuity

answered 29 mins ago Kavi Rama Murthy 249k

2

votes

1

answer

44

views

Reduction formula for $\int_0^1 x^m(1-x)^{n-1}\,\mathrm{d}x$?

reduction-formula

modified 31 mins ago user 19.5k

1

vote

1

answer

44

views

How to determine the envelope of some curves, that is a curve tangent to many ellipses

conic-sections tangent-curve

answered 33 mins ago qfwfq 250

7

votes

1

answer

34

views

$f(z)$ has no zeros on $|z|=r, r<1$

complex-analysis number-theory complex-numbers analytic-number-theory riemann-zeta

answered 35 mins ago Greg Martin 54.2k

0

votes

0

answers

5

views

Venn diagram shading

discrete-mathematics

asked 36 mins ago tom911 37

0

votes

1

answer

25

views

homeomorphism in $(-\infty,-1) ∪ [0,\infty)$ of $\mathbb{R}$

general-topology analysis continuity

answered 36 mins ago Henno Brandsma 193k

0

votes

0

answers

8

views

finding the umvue of variance of exponential distribution

statistics statistical-inference estimator

modified 39 mins ago smaillis 342

0

votes

0

answers

10

views

Complex Geometry

geometry complex-numbers complex-geometry

asked 40 mins ago Principia Mathematica 17

0

votes

0

answers

10

views

A reference for Nielsen's First Generalized Polynomial Expansion

combinatorics polynomials

modified 45 mins ago Sela 53

-2

votes

0

answers

14

views

A figure has been given below with shaded region. Pls find its area.

geometry area

asked 47 mins ago PCDE 1

0

votes

1

answer

13

views

Again quick questions of infinite series

calculus sequences-and-series

answered 50 mins ago DatBoi 2,247

0

votes

0

answers

5

views

Genus of a Canonical Product - Genus of a Torus

complex-analysis geometric-topology

asked 51 mins ago Matt Tucker 47

0

votes

1

answer

15

views

Evolution of angle between two triangles as they tilted towards each other

geometry trigonometry

answered 54 mins ago user10354138 26.3k

1

vote

2

answers

33

views

How many numbers greater than $4000$ can be formed using $0,2,4,5,7$?

combinatorics permutations

modified 56 mins ago Toby Mak 11.8k

0

votes

1

answer

14

views

Probability and source emission.

probability

modified 1 hour ago tommik 18.2k

0

votes

0

answers

23

views

How to extend $U$ to $\mathcal H\ $?

functional-analysis solution-verification operator-theory hilbert-spaces

modified 1 hour ago Anacardium 1,040

0

votes

0

answers

29

views

Evaluating $\lim_{x \to a} x^{x^x}$

limits

asked 1 hour ago NewbieToCoding 3

0

votes

0

answers

5

views

Multi step methods; Zero-stable

numerical-methods numerical-linear-algebra numerical-optimization numerical-calculus

asked 1 hour ago Ibara99 1

1

vote

0

answers

3

views

Example of Quasi-circular domain

complex-analysis several-complex-variables

asked 1 hour ago Shreedhar Bhat 563

0

votes

2

answers

12

views

Finding pairs of solutions to an equation with a prime number

number-theory elementary-number-theory prime-numbers

answered 1 hour ago fleablood 110k

0

votes

0

answers

16

views

If $f(x)$ irreducible degree $p$, over $\mathbb{Q}$ with exactly two nonreal roots in $\mathbb{C}$ Then the Galois group of $f(x)$ is $S_p.$

field-theory galois-theory

asked 1 hour ago eraldcoil 1,981

0

votes

0

answers

12

views

WolframAlpha evaluate something with each root of a polynomial

polynomials roots wolfram-alpha

asked 1 hour ago Will Kanga 11

0

votes

1

answer

15

views

Finding all Palindromes in decimal and binary smaller than 2^20

number-theory elementary-number-theory binary palindrome

answered 1 hour ago Mike Smith 1,036

8

votes

2

answers

228

views

$\frac{a^2+3b^2}{a+3b}+\frac{b^2+3c^2}{b+3c}+\frac{c^2+3a^2}{c+3a}\geqslant 3$

inequality optimization contest-math cauchy-schwarz-inequality

modified 1 hour ago Rodrigo de Azevedo 17.2k

1

vote

0

answers

17

views

Determine the solution of the following elliptical problem

partial-differential-equations fourier-analysis dynamical-systems fourier-series

modified 1 hour ago AndVld 113

0

votes

0

answers

9

views

$A^*$ is a free $A$-module

abstract-algebra c-star-algebras

asked 1 hour ago Dean Young 4,750

0

votes

0

answers

8

views

How's $\liminf a_n\leq \liminf \hat a_n \;(\;\leq\;)\;\limsup \hat a_n\leq \limsup a_n$ more general than $a_n\to \ell \implies \hat a_n\to \ell$?

real-analysis

modified 1 hour ago Trailing Stop 1

0

votes

1

answer

14

views

$\mathbb{R}/{\sim}$ is Frechet Urysohn, where $x \sim y \Leftrightarrow x = y \lor x,y \in \mathbb{Z}$

general-topology functional-analysis quotient-spaces

answered 1 hour ago Brian M. Scott 559k

1

vote

0

answers

55

views

Bound on the sum of eigenvalues

linear-algebra matrices eigenvalues-eigenvectors upper-lower-bounds symmetric-matrices

modified 1 hour ago Apprentice 423

1

vote

0

answers

15

views

Problems with computing a residue of a solution to an ODE

complex-analysis ordinary-differential-equations residue-calculus

modified 1 hour ago Ines Institoris 363

2

votes

0

answers

7

views

Computation with Gaussian measures on Hilbert spaces

functional-analysis measure-theory hilbert-spaces lebesgue-measure

asked 1 hour ago phaselead 21

0

votes

0

answers

8

views

On a conjectured upper bound for $k=\nu_q(N)$, if $N=q^k n^2$ is an odd perfect number with special prime $q$

number-theory upper-lower-bounds conjectures arithmetic-functions perfect-numbers

modified 1 hour ago Arnie Bebita-Dris 8,593

2

votes

0

answers

26

views

finite $\mathbb Z$ modules are also finitely generated $\mathbb Z$ algebras

algebraic-geometry commutative-algebra

modified 1 hour ago Soumyadip Sarkar 535

0

votes

0

answers

5

views

How do you prove that a set is not freely generated?

elementary-set-theory logic recursion

asked 1 hour ago why_did_i_do_this_course 1

0

votes

0

answers

25

views

Parametric calculus question that's stumping me.

calculus definite-integrals parametric

modified 1 hour ago Lando Jongeward 1

0

votes

1

answer

17

views

Elliptic curves and primes

prime-numbers elliptic-curves elliptic-equations

answered 1 hour ago Stahl 20.7k

0

votes

0

answers

6

views

Parabolic equations without compatibility conditions

partial-differential-equations parabolic-pde

asked 1 hour ago Yuval 2,419

0

votes

0

answers

25

views

What is the probability of choosing one letter from the alphabet correctly, ten times in a row?

probability

modified 1 hour ago CharlesT 1

1

vote

0

answers

32

views

Can Josephus avoid being a killer in the Josephus problem?

sequences-and-series combinatorics computer-science

modified 1 hour ago mic 129

0

votes

0

answers

10

views

Possible combinations from 3 column

combinations

asked 1 hour ago saeed 1

-1

votes

0

answers

11

views

A “trivial identity” about kernels of operators in a Hilbert space

operator-theory hilbert-spaces adjoint-operators

asked 1 hour ago Fei Cao 574

0

votes

0

answers

3

views

Regarding reductive operator on Hilbert space

hilbert-spaces compact-operators

asked 1 hour ago Noob mathematician 1,521

-2

votes

1

answer

33

views

soliving logrithmic simultaneius equation

logarithms systems-of-equations

modified 2 hours ago tahasozgen 157

1

vote

1

answer

26

views

Quick questions of infinite series

calculus infinite-product

modified 2 hours ago Soheil 2,695

1

vote

0

answers

18

views

Is the decimal component of the square root of 2 (i.e. sqrt(2) - 1) a named constant? Is it broadly significant?

geometry constants

asked 2 hours ago Matthew Milone 71

1

vote

1

answer

13

views

How can I find the standard deviation of the sum of a series of rolls of a weighted die?

statistics approximation standard-deviation

modified 2 hours ago Isaac Mammel 13

1

vote

2

answers

37

views

Is the space of polynomial isometric to $\mathbb R^n$?

functional-analysis isometry

modified 2 hours ago user1500178 127

1

vote

2

answers

25

views

Selecting at least three non consecutive integers from $\{x:x\le n; x,n\in\mathbb{N}\}$

combinatorics combinations

modified 2 hours ago true blue anil 23.3k

0

votes

0

answers

15

views

Is there any book regarding the collections of interviews with Fields medalists?

reference-request soft-question mathematicians

modified 2 hours ago J. W. Tanner 54.7k

7

votes

2

answers

154

views

Prove inequality $\tan \left( \frac\pi2 \frac{(1+x)^2}{3+x^2}\right) \tan \left( \frac\pi2 \frac{(1-x)^2}{3+x^2}\right)\le\frac13 $

calculus functional-analysis trigonometry inequality

modified 2 hours ago Quanto 51.9k

0

votes

1

answer

12

views

Permutation of Elements of a Countable Infinite Set Such That No Element Repeats a Position

elementary-set-theory set-theory

modified 2 hours ago Mashpa 105

0

votes

1

answer

13

views

Left Compatible with Ordinal Addition (Multiplication) for alephs

set-theory order-theory cardinals ordinals

answered 2 hours ago Noah Schweber 190k

1

vote

0

answers

16

views

Prove that the language is not context free

context-free-grammar

asked 2 hours ago Victoria Leshcheko 11

1

vote

0

answers

12

views

How do I sketch the step response given the poles and zeroes?

matlab control-theory

asked 2 hours ago young thug 11

1

vote

0

answers

37

views

Generalizing a property of $\mathbb Z_n$

ring-theory commutative-algebra

modified 2 hours ago GA316 3,800

1

vote

1

answer

18

views

Finding equilibrium point from a differential equation

calculus ordinary-differential-equations derivatives

answered 2 hours ago user1337 16.2k

2

votes

2

answers

36

views

Making Sense of the weighted Least Squares method from ordinary Least Squares

linear-algebra least-squares

modified 2 hours ago littleO 41.7k

2

votes

0

answers

21

views

connectedness of adic spaces

number-theory p-adic-number-theory

modified 2 hours ago Xq. Yang 21

5

votes

0

answers

52

views

Interesting behavior of $\{a\rightarrow abc,b\rightarrow ab,c\rightarrow c\}$

sequences-and-series substitution computational-mathematics

modified 2 hours ago Trevor 3,613

1

vote

1

answer

20

views

Some questions regarding the Asymptotic Winding of the Geodesic Flow on Modular Surfaces and Continuous Fractions. Y. Guivarc'h and Y. Le Jan

dynamical-systems hyperbolic-geometry quotient-spaces modular-forms geodesic

modified 2 hours ago Neil hawking 1,313

1

vote

2

answers

28

views

Probability that the product of two numbers in $\{0,1,…,10^{n - 1}\}$ contains $2n - k$ digits, $k = 0,1,…$

probability number-theory probability-theory statistics discrete-mathematics

modified 3 hours ago user2661923 8,396

1

vote

0

answers

36

views

On the infinitesimals.

calculus nonstandard-analysis infinitesimals

modified 3 hours ago J. W. Tanner 54.7k

0

votes

0

answers

13

views

Example of a compact rank one operator

functional-analysis operator-theory operator-algebras

asked 3 hours ago Toasted_Brain 582

0

votes

0

answers

13

views

If I know the mean and median values of a distribution, can I determine the n'th percentile value?

statistics probability-distributions statistical-inference

asked 3 hours ago Peggy Schafer 19

0

votes

0

answers

9

views

Is the sum of skew-derivations a skew-derivation?

ring-theory definition noncommutative-algebra

asked 3 hours ago Jaca 229

1

vote

1

answer

28

views

First order logic. Describing that there exists a set with exactly 2 elements

elementary-set-theory logic first-order-logic predicate-logic quantifiers

modified 3 hours ago Robert Shore 11.8k

0

votes

0

answers

11

views

A comlete graph with n vertices is n-chromatic

combinatorics graph-theory coloring

modified 3 hours ago RobPratt 21.7k

1

vote

0

answers

8

views

Travelling (soliton) Wave solution to 1D GPE equation

ordinary-differential-equations partial-differential-equations nonlinear-system quantum-mechanics wave-equation

asked 3 hours ago Ethan 11

1

vote

0

answers

10

views

Can a complex differential equation of the second order exhibit chaotic behavior?

complex-analysis ordinary-differential-equations chaos-theory

asked 3 hours ago Pavlo. B. 41

0

votes

0

answers

7

views

fourier analysis : coefficients and phase of quasiperiodic signal

fourier-analysis harmonic-analysis quasiperiodic-function

modified 3 hours ago shomikc 1

1

vote

0

answers

17

views

Quotients between groups and their abelianizations commute

abstract-algebra group-theory category-theory quotient-group

modified 3 hours ago Descartes Before the Horse 5,852

0

votes

1

answer

14

views

Non-standard model of naturals and Löwenheim–Skolem

logic model-theory nonstandard-analysis nonstandard-models

modified 3 hours ago Alex Kruckman 47.7k

4

votes

0

answers

25

views

Solving Friedmann equation for a(t) in quintessence universe

integration

modified 4 hours ago ObiDonKenobi 71

4

votes

2

answers

1k

views

Definition of Normal Bundle

algebraic-topology vector-bundles

modified 4 hours ago Satya Mandal 1

1

vote

1

answer

17

views

Question of rank of a matrix $4\times 6$

linear-algebra matrices complex-numbers matrix-rank

modified 4 hours ago Priya 143

1

vote

1

answer

195

views

1-dimensional Linear System of Divisors of Degree 2 is Complete

algebraic-geometry riemann-surfaces divisors-algebraic-geometry

modified 5 hours ago Jasmine Guan 1

3

votes

0

answers

13

views

Boolean valued models in a general setting

set-theory model-theory boolean-algebra algebraic-logic

asked 5 hours ago Severine Climacus 51

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