Q&A - Mathematics

71%

+3 −0

What is an example of a pathological imbedding of a(n allowed) graph into an oriented surface?

1 answer · posted 1y ago by The Amplitwist‭ · last activity 11mo ago by The Amplitwist‭

60%

+1 −0

How do I unambiguously define the facial circuits in a

2

-cell embedding of a graph into a surface?

1 answer · posted 12mo ago by The Amplitwist‭ · last activity 11mo ago by The Amplitwist‭

topology graph-theory

44%

+2 −3

Cyclical or “loop” fractals?

2 answers · posted 1y ago by Julius H.‭ · last activity 11mo ago by pbloem‭

real-analysis fractal

66%

+2 −0

Seeking a theorem about lattices

1 answer · posted 11mo ago by WheatWizard‭ · last activity 11mo ago by Lisanne‭

linear-algebra reference-request free-abelian-group

77%

+5 −0

How to find perfect squares such that their base 9 representation is all 1s?

1 answer · posted 11mo ago by CrSb0001‭ · last activity 11mo ago by Lisanne‭

number-theory bases recreational-mathematics

71%

+3 −0

Is it possible to find a solution for any

a e^{b x} + c x + d = 0

?

0 answers · posted 11mo ago by CrSb0001‭

calculus recreational-mathematics

71%

+3 −0

Is there a

Δ

-complex structure on the sphere with less than three

0

-simplices?

1 answer · posted 12mo ago by The Amplitwist‭ · last activity 12mo ago by Derek Elkins‭

algebraic-topology delta-complex

42%

+1 −2

What is the significance of the K-axiom in modal logic S5?

1 answer · posted 1y ago by Julius H.‭ · edited 12mo ago by xamidi‭

modal-logic proof-theory hilbert-systems axioms

54%

+4 −3

Defining Bayes’s theorem from scratch in ZFC

1 answer · posted 1y ago by Julius H.‭ · last activity 12mo ago by xamidi‭

set-theory zfc bayes-theorem

50%

+1 −1

Prove that

\forall x \in R : ⌊ x^{2} ⌋ - ⌊ r x ⌋ \geq - 1 ⟺ | r | \leq 2

.

1 answer · posted 1y ago by TheCodidacter, or rather ACodidacter‭ · last activity 12mo ago by Derek Elkins‭

inequality solution-verification

71%

+3 −0

Using convexity in the proof of Hölder’s inequality

1 answer · posted 1y ago by Snoopy‭ · last activity 1y ago by Snoopy‭

real-analysis

66%

+2 −0

Does {7,4|3} have a realization on the Klein quartic?

0 answers · posted 1y ago by WheatWizard‭

polytopes algebraic-geometry

66%

+2 −0

Find length

M P

in trapezoid

0 answers · posted 1y ago by TheCodidacter, or rather ACodidacter‭ · edited 1y ago by TheCodidacter, or rather ACodidacter‭

geometry

22%

+0 −5

What are the Peano axioms?

1 answer · posted 1y ago by Julius H.‭ · last activity 1y ago by rmf‭

logic

66%

+2 −0

The Fourier transform of

1 / p^{3}

1 answer · posted 1y ago by C-T‭ · last activity 1y ago by LL 3.14‭

complex-analysis calculus multivariable-calculus integration fourier-analysis

71%

+3 −0

Besov or Triebel-Lizorkin spaces versus Lorentz spaces

0 answers · posted 1y ago by LL 3.14‭ · edited 1y ago by LL 3.14‭

interpolation Besov-space functional-analysis

28%

+0 −3

What is a “first-order substructural logic that has a cut-free sequent calculus”?

1 answer · posted 1y ago by Julius H.‭ · last activity 1y ago by Dan Doel‭

logic

40%

+0 −1

What is a one-variable fragment of first-order logic?

0 answers · posted 1y ago by Julius H.‭

logic

66%

+2 −0

matrix inverse of

I + A

where

A

is skew-symmetric

1 answer · posted 1y ago by Trevor‭ · last activity 1y ago by Trevor‭

linear-algebra

42%

+1 −2

Explain derived categories to someone without a strong background in homological algebra [closed]

0 answers · posted 1y ago by Julius H.‭ · closed 1y ago by Peter Taylor‭

category-theory

28%

+0 −3

What is a dual object? [closed]

0 answers · posted 1y ago by Julius H.‭ · closed 1y ago by Peter Taylor‭

category-theory

66%

+4 −1

is arithmetic finitely consistent?

0 answers · posted 1y ago by Jason‭

proof logic peano-arithmetic incompletness consistency

66%

+2 −0

A program which could derive theorems given formation rules in any modal logic?

1 answer · posted 1y ago by Julius H.‭ · edited 1y ago by Peter Taylor‭

computational-mathematics proof-assistants

71%

+3 −0

Concrete examples of set theorists thinking independence proofs only determine provability rather than that a statement is neither true nor false?

1 answer · posted 1y ago by Julius H.‭ · last activity 1y ago by Peter Taylor‭

set-theory

50%

+1 −1

What are the “increasingly stable consequences of the large cardinal hierarchy”?

0 answers · posted 1y ago by Julius H.‭

set-theory

66%

+2 −0

Fourier transform of an

L^{1}

function is uniformly continuous

1 answer · posted 1y ago by Snoopy‭ · edited 1y ago by Snoopy‭

real-analysis fourier-analysis

37%

+1 −3

Are these introductory logic textbooks wrong to teach ‘unless’ = ‘or’? [duplicate]

0 answers · posted 1y ago by 8500 Ward‭ · closed as duplicate 1y ago by Peter Taylor‭

logic

66%

+2 −0

For any real number

m

,

| \sum_{n = 1}^{\infty} \frac{m}{n^{2} + m^{2}} | < \frac{π}{2}

1 answer · posted 1y ago by Snoopy‭ · last activity 1y ago by Snoopy‭

calculus real-analysis

71%

+3 −0

If both

lim_{x \to \infty} f (x)

and

lim_{x \to \infty} f^{'} (x)

exist, then

lim_{x \to \infty} f^{'} (x) = 0

.

1 answer · posted 1y ago by Snoopy‭ · last activity 1y ago by Snoopy‭

real-analysis

57%

+2 −1

Strange behavior in elections and pie charts

2 answers · posted 1y ago by TheCodidacter, or rather ACodidacter‭ · last activity 1y ago by Hudjefa‭

probability

66%

+2 −0

sup (A \cdot B) = (sup A) (sup B)

where

A

and

B

bounded sets of positive real numbers

3 answers · posted 1y ago by Snoopy‭ · edited 1y ago by Snoopy‭

real-analysis supremum-infimum

60%

+1 −0

Why is

\int_{0}^{\infty} | \frac{\sin x}{x} | d x = \infty

?

1 answer · posted 1y ago by Snoopy‭ · last activity 1y ago by Snoopy‭

real-analysis improper-integral

71%

+3 −0

Is there a

(n_{3})

configuration which is not self-dual?

1 answer · posted 1y ago by WheatWizard‭ · last activity 1y ago by Peter Taylor‭

combinatorics

25%

+0 −4

Picking 20 different numbers, in the same draw

vs.

picking 10 different numbers, in 2 different draws.

1 answer · posted 1y ago by H7D‭ · last activity 1y ago by Olin Lathrop‭

lottery

66%

+2 −0

Is the nth Betti number determined by orientability?

1 answer · posted 1y ago by WheatWizard‭ · edited 1y ago by WheatWizard‭

betti-numbers algebraic-topology

80%

+6 −0

What is special about the 11-cell and 57-cell?

1 answer · posted 2y ago by WheatWizard‭ · last activity 1y ago by ziggurism‭

polytopes

22%

+0 −5

How can school children intuit why over 100, D is larger? But under 100, D% is larger?

2 answers · posted 2y ago by Chgg Clou‭ · last activity 1y ago by Hudjefa‭

high-school-mathematics

75%

+4 −0

Is there a statistical method to identify the type of outliers shown in the pictures attached to my question?

1 answer · posted 1y ago by Ivan Nepomnyashchikh‭ · last activity 1y ago by Hudjefa‭

statistics

33%

+0 −2

(\forall ε > 0 : | a - b | < ε) ⟺ a = b

vs.

(\forall ε > 0 : a \leq b + ε) ⟺ a \leq b

1 answer · posted 1y ago by deleted user · edited 1y ago by Peter Taylor‭

inequality

50%

+0 −0

Calculation of limit

0 answers · posted 1y ago by Klein Moretti‭

calculus analysis limits applied-mathematics

25%

+0 −4

How can I improve contrast of red and green, to prove Reverse Triangle Inequality?

1 answer · posted 1y ago by deleted user · last activity 1y ago by Peter Taylor‭

visualization

37%

+1 −3

Solely by eye, how can 16 year olds visually distinguish

\vec{b} - \vec{r}

from

| \vec{b} | - | \vec{r} |

?

2 answers · posted 1y ago by deleted user · last activity 1y ago by Olin Lathrop‭

visualization

40%

+0 −1

While pictorializing

| x - y | < | x + y |

, how can 1 picture simultaneously prove (Reverse) △ Inequalities,

| x - y | \leq | x | + | y |, | x | - | y | \leq | x - y |

? [duplicate]

0 answers · posted 1y ago by deleted user · closed as duplicate 1y ago by Peter Taylor‭

visualization

75%

+4 −0

Is it possible to show that a normalised random variable has zero mean and unit variance?

0 answers · posted 1y ago by mr Tsjolder‭ · edited 1y ago by mr Tsjolder‭

statistics expectation

33%

+1 −4

25% probability that there was a chance of avoiding injury

vs.

25% chance of avoiding injury

2 answers · posted 2y ago by DNB‭ · last activity 1y ago by Hudjefa‭

probability

81%

+7 −0

How can I choose a point from a uniform distribution within a regular polygon?

2 answers · posted 1y ago by Karl Knechtel‭ · last activity 1y ago by trichoplax‭

plane-geometry applied-mathematics sampling

77%

+5 −0

Notation for one-sided hypothesis testing

1 answer · posted 3y ago by tommi‭ · last activity 1y ago by Glen_b‭

statistics notation hypothesis-testing

42%

+1 −2

Picture proof for expansion of

x^{n} - y^{n}

2 answers · posted 1y ago by Este‭ · last activity 1y ago by Peter Taylor‭

visualization

42%

+1 −2

1 picture proof for the triangle inequality and the reverse triangle inequality

0 answers · posted 1y ago by Este‭ · edited 1y ago by trichoplax‭

visualization

71%

+3 −0

Classification for involutory real infinite series

1 answer · posted 1y ago by nsajko‭ · last activity 1y ago by Peter Taylor‭

classification real-analysis inverse polynomials series

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