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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.

336 posts   RSS
Activity Age Score Random
Filters (None)
80%
+6 −0
Criteria for solvable Minesweeper game?

0 answers  ·  posted 10mo ago by Olin Lathrop‭  ·  edited 10mo ago by Olin Lathrop‭

algorithm
71%
+3 −0
The gcd of powers in a gcd domain

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

abstract-algebra
14%
+0 −10
How can 3/1 ≡ 1/(1/3), when left side features merely integers, but right side features a repetend?

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

arithmetical-hierarchy
22%
+0 −5
At what jackpot minimum is playing Lottario rational?

1 answer  ·  posted 1y ago by Chgg Clou‭  ·  edited 1y ago by Chgg Clou‭

lottery
22%
+0 −5
How to intuit that if you destroy someone else's lottery ticket, you didn't deprive her of a chance of winning the lottery?

0 answers  ·  posted 12mo ago by DNB‭  ·  edited 12mo ago by DNB‭

lottery
81%
+7 −0
Endomorphisms on an entropic structure whose pointwise product is the identity automorphism - entropic idempotent structure?

0 answers  ·  posted 2y ago by Prime Mover‭  ·  edited 2y ago by Prime Mover‭

abstract-algebra
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
33%
+0 −2
How to intuit, construe multiplicands and multiplicators $\le 10$ resulting from $\dbinom pc$, WITHOUT division or factorials? [duplicate]

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

combinatorics
71%
+3 −0
Notation for nested exponents

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

notation exponents
70%
+5 −1
equilateral triangle inscribed in an ellipse

2 answers  ·  posted 2y ago by msh210‭  ·  last activity 2y ago by Anonymous‭

conics triangle
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
28%
+0 −3
Expanding the Integration problem.

1 answer  ·  posted 1y ago by Anonymous‭  ·  last activity 1y ago by TextKit‭

integration
60%
+1 −0
What's the common ratio for this geometric sequence?

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

geometric-sequence sequence
75%
+4 −0
$\int_{E_n} |g|^q = \left| \int_E \chi_{E_n}\cdot \text{sgn}(g)\cdot g \cdot |g|^{q-1}\cdot |g| \right|$

0 answers  ·  posted 2y ago by whybecause‭  ·  edited 2y ago by Derek Elkins‭

real-analysis Lp-space
77%
+5 −0
Is $f(x)=\sin(x)$ the unique function satisfying $f'(0)=1$ and $f^{(n)}(\Bbb R)\subset [-1,1]$ for all $n=0,1,\ldots$?

1 answer  ·  posted 1y ago by Grove‭  ·  edited 1y ago by Pavel Kocourek‭

derivatives real-analysis
22%
+0 −5
How can school children intuit why over 100, D is larger? But under 100, D% is larger?

2 answers  ·  posted 1y ago by Chgg Clou‭  ·  last activity 5mo ago by Agent Smith‭

high-school-mathematics
22%
+0 −5
Isn't Ontario 49 always worse than Daily Grand? [closed]

0 answers  ·  posted 1y ago by Chgg Clou‭  ·  closed 1y ago by Peter Taylor‭

lottery
50%
+1 −1
Acceptable, usual to write $\ge 2$ pipes simultaneously?

1 answer  ·  posted 2y ago by DNB‭  ·  last activity 2y ago by Derek Elkins‭

probability
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
71%
+3 −0
"Pointwise equicontinuity implies uniform" implies compact

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

real-analysis equicontinuity continuity metric-spaces
75%
+4 −0
What is the probability that the convex hull of $n$ randomly distributed points has $l$ of the points on its boundary?

1 answer  ·  posted 1y ago by siric‭  ·  edited 1y ago by tommi‭

probability convex-hull
20%
+0 −6
Without trial and error, average(average(a,b),c) vs. average(a,average(b,c)). [closed]

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

arithmetic
71%
+3 −0
Prove $e^x \ge x+1 \\\; \forall x \in \mathbb{R}$ using induction

1 answer  ·  posted 1y ago by Carefree Explorer‭  ·  edited 1y ago by Derek Elkins‭

limits induction inequality solution-verification
50%
+0 −0
A discrete-time queue Markov Chain problem

0 answers  ·  posted 2y ago by Joe‭

Markov-chains
75%
+4 −0
Proving that $p\mid (p+1776)$ if $p$ is a prime and $p(p+1776)$ is a perfect square

2 answers  ·  posted 1y ago by Snoopy‭  ·  last activity 1y ago by Snoopy‭

number-theory algebra
71%
+3 −0
How to calculate remaining volume of a wire spool

2 answers  ·  posted 1y ago by re89j‭  ·  last activity 1y ago by Olin Lathrop‭

geometry volume
80%
+6 −0
What is the Name of Function for Probability of a Certain Sum on Random Die Rolls?

1 answer  ·  posted 1y ago by James McLellan‭  ·  last activity 1y ago by Derek Elkins‭

statistics
60%
+1 −0
Is there a "regular" quasi-convex function $f:\Bbb R^2 \to \Bbb R$ that is not a monotone transformation of any convex function?

0 answers  ·  posted 1y ago by Pavel Kocourek‭

multivariable-calculus real-analysis convex-analysis monotone-functions
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
71%
+3 −0
Show that $f(x) = \arctan\left(\frac{x}{x+1}\right) + \arctan\left(\frac{x+1}{x}\right) = \frac{\pi}{2}$

2 answers  ·  posted 1y ago by Carefree Explorer‭  ·  last activity 1y ago by Derek Elkins‭

limits trigonometry
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%
+3 −3
Isn't "any, some, or all" redundant? Why not write just "any"?

1 answer  ·  posted 2y ago by Chgg Clou‭  ·  last activity 2y ago by Tim Pederick‭

terminology
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
$g(x)\xrightarrow{x\to\infty}\infty$ Implies $g'(x)\leq g^{1+\varepsilon}(x)$

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

calculus
50%
+0 −0
Is there a way to encode a unique arrangement of vertices of a graph with a unique short word?

2 answers  ·  posted 1y ago by Carefree Explorer‭  ·  last activity 1y ago by celtschk‭

graph-theory
28%
+0 −3
How can Cross Multiplication be intuited or pictured? [closed]

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

arithmetic
30%
+1 −5
What did James Stewart mean by "the line integral reduces to an ordinary single integral in this case" ?

2 answers  ·  posted 1y ago by TextKit‭  ·  edited 1y ago by trichoplax‭

line-integral
75%
+4 −0
Is it impossible to prove Jensen's inequality by way of step functions?

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

real-analysis convex-analysis Jensen's-inequality
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
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
Why would skyrocketing the numbers of doors help laypeople intuit the Monty Hall Problem?

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

probability
42%
+1 −2
Is $r \times \frac{d}{dt} mv=\frac{d}{dt} (r \times mv)$

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

differentiation
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
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
81%
+7 −0
Does this construction always give a topological vector space?

0 answers  ·  posted 2y ago by celtschk‭  ·  edited 2y ago by r~~‭

topology linear-algebra topological-vector-spaces
50%
+1 −1
How to deduce which ETF is redundant? a of ETF1's holdings in ETF3, a of ETF2 in ETF3, b of ETF1 are in ETF2, b of ETF2 in ETF1.

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

finance
33%
+1 −4
How can you "easily see that such squares [of side length $\sqrt{13}$ and $\sqrt{18}$] will not fit into the [4 × 4] grid"?

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

geometry
75%
+4 −0
Missing a solution: Are A and B always equal if A-B=0

3 answers  ·  posted 2y ago by re89j‭  ·  last activity 2y ago by tommi‭

logic equation algebra problem
50%
+0 −0
Why does the Dottie number $=\sqrt{1-\left(2\text I^{-1}_\frac12\left(\frac12,\frac32\right)-1\right)^2}$?

0 answers  ·  posted 2y ago by Tyma Gaidash‭  ·  edited 2y ago by Tyma Gaidash‭

probability equation median inverse
33%
+0 −2
For (a variation) of the Monty Hall problem, what permits you to repaint doors 2 and 3? What permits you to replace p with $1 - p$?

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

probability
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