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General Q&A about all branches of theoretical and applied mathematics, including closely-adjacent sciences where the central question is about the math.

339 posts   RSS
Activity Age Score Random
Filters (None)
60%
+1 −0
What does upper indices represent?

2 answers  ·  posted 2y ago by deleted user  ·  last activity 2y ago by r~~‭

notation tensors
40%
+0 −1
How to find constant equal to what in integration?

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by deleted user

classical-mechanics integration
33%
+2 −6
Can we add without using addition?

3 answers  ·  posted 2y ago by General Sebast1an‭  ·  last activity 2y ago by DavidCary‭

equation arithmetic
85%
+10 −0
Complex numbers in 2D, quaternions in 4D, why nothing in 3D?

2 answers  ·  posted 2y ago by Fred Wamsley‭  ·  last activity 2y ago by Derek Elkins‭

quaternions
80%
+6 −0
Does there exist a non-zero game such that the sum of three or more copies of it is zero?

0 answers  ·  posted 1y ago by celtschk‭

combinatorial-game-theory
28%
+0 −3
In the Lost Boarding Pass Probability Problem, why couldn't Passengers 2-99 sit in Seats 1 or 100, before Passenger 100 boards?

0 answers  ·  posted 3y ago by DNB‭  ·  edited 3y ago by DNB‭

probability
60%
+1 −0
How $ijk=\sqrt{1}$?

2 answers  ·  posted 2y ago by deleted user  ·  last activity 2y ago by Tim Pederick‭

quaternions
40%
+0 −1
If C = Calvin wins the match, and $X \thicksim Bin(2, p) =$ how many of the first 2 games he wins — then why P(C|X = 1) = P(C)?

1 answer  ·  posted 2y ago by DNB‭  ·  last activity 2y ago by Peter Taylor‭

probability
75%
+4 −0
Is this formula for the minimal sum correct?

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

set-theory ordinal-numbers
71%
+3 −0
What're the orders for equation expressing?

2 answers  ·  posted 2y ago by General Sebast1an‭  ·  last activity 2y ago by r~~‭

exponent equation order grouping arithmetic
33%
+0 −2
Out of 4 people, why does ways to choose a 2-person committee overcount by 2 the ways to divide the 4 into 2 teams of 2?

1 answer  ·  posted 3y ago by DNB‭  ·  last activity 2y ago by Tim Pederick‭

probability
40%
+0 −1
How do you calculate $P(X = n|G), P(X = n|G^C)$ by the Law of Total Probability, with extra conditioning?

0 answers  ·  posted 3y ago by DNB‭  ·  edited 2y ago by Wolgwang‭

probability
33%
+0 −2
Intuitively, why does $p$ vary inversely with $P(C_3 \mid D_2)$? But directly with $P(C_2 \mid D_3)$?

1 answer  ·  posted 2y ago by DNB‭  ·  last activity 2y ago by whybecause‭

probability
66%
+2 −0
Do these major triangle lines have names?

0 answers  ·  posted 2y ago by Peter Taylor‭

euclidean-geometry triangle plane-geometry nomenclature
71%
+3 −0
What does the distribution of a strictly increasing random walk look like if you stop at `N` steps?

0 answers  ·  posted 2y ago by SherlockSage‭  ·  edited 2y ago by SherlockSage‭

combinatorics
50%
+1 −1
Rules of checking differentiability for Rolle's theorem

0 answers  ·  posted 3y ago by deleted user  ·  edited 3y ago by deleted user

calculus real-analysis limits differentiability rolle's-theorem
40%
+0 −1
How to visualize division in the Odds form of Bayes's Theorem?

0 answers  ·  posted 2y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
71%
+3 −0
Given two angles of a triangle, finding an angle formed by a median

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

euclidean-geometry vector
60%
+1 −0
What's the common ratio for this geometric sequence?

1 answer  ·  posted 2y ago by General Sebast1an‭  ·  last activity 2y ago by tommi‭

geometric-sequence sequence
40%
+0 −1
To correct for overcounting, why can't we divide by the sum of the over-counts? [duplicate]

0 answers  ·  posted 2y ago by DNB‭  ·  closed as duplicate 2y ago by Peter Taylor‭

combinatorics
80%
+6 −0
$g(x)\xrightarrow{x\to\infty}\infty$ Implies $g'(x)\leq g^{1+\varepsilon}(x)$

3 answers  ·  posted 2y ago by Udi Fogiel‭  ·  last activity 2y ago by Peter Taylor‭

calculus
37%
+1 −3
How can you analogize mathematical induction to dominoes falling, if some domino can fail to topple? [closed]

1 answer  ·  posted 2y ago by Chgg Clou‭  ·  closed 2y ago by Peter Taylor‭

induction
50%
+0 −0
If Alice must've have classes on at least 2 days, why do you need the intersection of 3 $A_i^C$'s? [closed]

0 answers  ·  posted 3y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
71%
+3 −0
Notation for nested exponents

1 answer  ·  posted 2y ago by JRN‭  ·  last activity 2y ago by leovt‭

notation exponents
33%
+0 −2
Why's the true positive rate termed Sensitivity and true negative rate Specificity, not vice versa? [closed]

0 answers  ·  posted 2y ago by DNB‭  ·  closed 2y ago by Peter Taylor‭

probability
80%
+6 −0
How to show if a set is simply connected?

1 answer  ·  posted 3y ago by kreijstal‭  ·  last activity 3y ago by Derek Elkins‭

complex-analysis
50%
+0 −0
Is $x=\int \int \ddot{x}\mathrm dx \mathrm dx$?

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by celtschk‭

multivariable-calculus
42%
+1 −2
In $w_{k + 1} - w_k = (\frac{1 - p}{p})^{exponent}(w_1 - w_0)$, why isn't exponent $k + 1$?

1 answer  ·  posted 2y ago by DNB‭  ·  last activity 2y ago by leovt‭

probability
40%
+0 −1
What to do when there's lot of function of time? (For integration) Should I consider them as constant?

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by r~~‭

integration
50%
+0 −0
A discrete-time queue Markov Chain problem

0 answers  ·  posted 2y ago by Joe‭

Markov-chains
33%
+0 −2
If k = 1, why $n(n-1) \dots \color{red}{(n-k+1)} = n$?

1 answer  ·  posted 3y ago by DNB‭  ·  edited 3y ago by DNB‭

probability
60%
+1 −0
differentiate under integral sign says something went wrong

1 answer  ·  posted 3y ago by deleted user  ·  last activity 3y ago by celtschk‭

calculus multivariable-calculus differentiation integration improper-integral
40%
+0 −1
How to visualize multiplication in the Odds form of Bayes's Theorem?

0 answers  ·  posted 2y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
33%
+0 −2
If a 2nd test's independent from the 1st test, then why does $\frac{0.95}{0.05}$ figure twice in $\frac{P(D|T_1)}{P(D^C|T_1)}\frac{P(T_2|D,T_1)}{P(T_2|D^C,T_1)}$?

0 answers  ·  posted 2y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
66%
+2 −0
$\sum_{k=0}^{n} \binom{n}{k}=2^{n} \overset{?}{\iff} \sum_{k=0}^{n} \binom{2n+1}{k}=2^{2n}$

1 answer  ·  posted 3y ago by DNB‭  ·  edited 3y ago by DNB‭

combinatorics
33%
+0 −2
How do mathematicians measure area for points?

1 answer  ·  posted 2y ago by deleted user  ·  last activity 2y ago by zavier‭

geometry area point border perimeter
25%
+0 −4
Why "only 1/10,000 men with wives they abuse subsequently murder them" ≠ P(A|G,M) & "50% of husbands who murder their wives abused them” ≠ P(G|A)?

0 answers  ·  posted 2y ago by DNB‭

probability
77%
+5 −0
Getting backward of partial differentiation's chain rule

3 answers  ·  posted 2y ago by deleted user  ·  last activity 2y ago by Derek Elkins‭

multivariable-calculus differentiation chain-rule
28%
+0 −3
How do these 3 bell curves of Likelihood, Posterior, Prior pictorialize the Odds form of Bayes' rule?

0 answers  ·  posted 2y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
28%
+0 −3
Besides guaranteeing 0 ≤ P(A ∩ B) ≤ 1, why can't Independence be defined as P(A ∩ B) = P(A) +,-, or ÷ P(B)?

1 answer  ·  posted 3y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
71%
+3 −0
Find limits of integration in polar coordinates

2 answers  ·  posted 2y ago by MissMulan‭  ·  last activity 2y ago by r~~‭

calculus double-integrals polar
28%
+0 −3
If a repair on a vessel costs $2$ and fully repaired vessel is worth $1$, don't we need know worth of broken vessel to decide whether to repair?

0 answers  ·  posted 3y ago by Chgg Clou‭  ·  edited 2y ago by Wolgwang‭

basic
71%
+3 −0
Maximize Independent Variable of Matrix Multiplication

1 answer  ·  posted 2y ago by Josh Hyatt‭  ·  edited 2y ago by Josh Hyatt‭

matrices vector
28%
+0 −3
Why shouldn't the Bose-Einstein value be used to calculate birthday probabilities?

0 answers  ·  posted 3y ago by DNB‭

probability
33%
+0 −2
Does "both girls, ≥ 1 winter girl" = "both girls, ≥ 1 winter child" let you generalize the problem statement that postulated both children as girls?

0 answers  ·  posted 2y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
77%
+5 −0
Notation for one-sided hypothesis testing

1 answer  ·  posted 2y ago by tommi‭  ·  last activity 8mo ago by Glen_b‭

statistics notation hypothesis-testing
33%
+0 −2
Why's Pr(the running total of a fair dice rolled repeatedly = n) = $\frac16 (p_{n-1} + p_{n-2} + p_{n-3} + p_{n-4} + p_{n-5} + p_{n-6})$?

0 answers  ·  posted 2y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
71%
+3 −0
Is Pythagorean theorem really valid in higher dimensional space?

2 answers  ·  posted 2y ago by deleted user  ·  edited 2y ago by zavier‭

pythagoras right-triangle
28%
+0 −3
How do I prove Simpson's Paradox, scilicet $P(A|B) > P(A|B^C)$?

0 answers  ·  posted 2y ago by DNB‭  ·  edited 2y ago by DNB‭

probability
50%
+0 −0
transpose matrix and general matrix is completely messed up

1 answer  ·  posted 2y ago by deleted user  ·  edited 2y ago by Peter Taylor‭

matrices matrix-transpose
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