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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.

445 posts RSS
Activity Age Score Random
Filters (None)
60%
+1 −0
Complex functions and inner product $\langle \frac{\partial f}{\partial z} , g\rangle $

2 answers  ·  posted 2y ago by Richard‭  ·  last activity 2y ago by Richard‭

complex-analysis summation integral functional-analysis
42%
+1 −2
Search & Probability

2 answers  ·  posted 2y ago by Hudjefa‭  ·  last activity 2y ago by Olin Lathrop‭

probability
71%
+3 −0
Is there a closed formula for multiplication of imaginary units in the direct limit of the Cayley-Dickson construction?

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

algebra
71%
+3 −0
Find the value of $\sum_{k=1}^\infty\frac{k^2}{k!}$

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

complex-analysis real-analysis series
66%
+2 −0
What does it mean by saying that $C([0,1])$ is a subset of $L^\infty([0,1])$?

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

real-analysis
80%
+6 −0
Does this generalization of path-connectedness also cover general connectedness?

1 answer  ·  posted 5y ago by celtschk‭  ·  last activity 2y ago by ronno‭

topology connectedness
50%
+0 −0
Find all functions (f:\mathbb N\to\mathbb N) such that for all primes (p), (p\mid f(a)^{f(p)}-f(b)^p\iff p\mid a-b)

0 answers  ·  posted 2y ago by TheCodidacter, or rather ACodidacter‭  ·  edited 2y ago by TheCodidacter, or rather ACodidacter‭

functions solution-verification modular-arithmetic
71%
+3 −0
Am I taking the antiderivative of |x| correctly?

1 answer  ·  posted 2y ago by CrSb0001‭  ·  edited 2y ago by The Amplitwist‭

calculus integration recreational-mathematics
33%
+1 −4
Without trial and error, how can I effortlessly deduce all $n, k_i ∈ ℕ ∋ \binom n {k_1, k_2, ..., k_n} =$ given c?

1 answer  ·  posted 3y ago by Chgg Clou‭  ·  edited 2y ago by Michael Hardy‭

combinatorics
77%
+5 −0
What is the probability density function for the tau distribution?

2 answers  ·  posted 3y ago by mr Tsjolder‭  ·  last activity 2y ago by Michael Hardy‭

statistics distributions
66%
+2 −0
Example of $f:[0,1]\to\mathbf{R}$ with $\lim_{a\to 0^+}\int_a^1f(x)dx=L $ for some real number $L$ but $\int_0^1|f(x)|dx=\infty $

2 answers  ·  posted 4y ago by Snoopy‭  ·  last activity 2y ago by Michael Hardy‭

real-analysis improper-integral
75%
+4 −0
Is it known whether most numbers are normal or not

1 answer  ·  posted 3y ago by Grove‭  ·  last activity 2y ago by Michael Hardy‭

number-theory
71%
+3 −0
The derivatives of a function at a boundary point

2 answers  ·  posted 2y ago by tommi‭  ·  last activity 2y ago by Michael Hardy‭

derivatives real-analysis
44%
+2 −3
How can you forebode that the answer shall be independent of the number of sides of the base of the polygon ?

1 answer  ·  posted 2y ago by Sunny‭  ·  last activity 2y ago by Michael Hardy‭

calculus
70%
+5 −1
Minimal non-standard number in non-standard models of PA

2 answers  ·  posted 2y ago by Aditya‭  ·  last activity 2y ago by Michael Hardy‭

logic model peano-arithmetic nonstandard-models
71%
+3 −0
$\liminf (a_n+b_n) = \liminf(a_n)+\liminf(b_n)$ provided that $\lim a_n$ exists

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

real-analysis limits
72%
+6 −1
What is the formula for sample standard deviation of a small sample size?

3 answers  ·  posted 3y ago by Ivan Nepomnyashchikh‭  ·  last activity 2y ago by Peter Taylor‭

statistics
66%
+2 −0
Why does the method of separating variables work?

2 answers  ·  posted 2y ago by The Amplitwist‭  ·  last activity 2y ago by Snoopy‭

partial-differential-equations separation-of-variables
50%
+0 −0
How can we prove that a point that follows another point has the same trajectory given a contant angle and ratio?

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

geometry vector
75%
+4 −0
Formalizing proof of existence of roots of functional equation

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

algebra functional-analysis
28%
+0 −3
How can I improve this tree diagram, for the Multivariable Chain Rule with all partial derivatives? [duplicate]

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

multivariable-calculus
44%
+2 −3
How can you forebode that amount of wood in a napkin ring is the same, regardless of the size of the sphere used ?

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

intuition calculus
28%
+0 −3
Why do students mix up addition and multiplication, in the Multivariable Chain Rule with all partial derivatives?

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

multivariable-calculus
60%
+1 −0
Interpreting $\text{Prop}$ in Set

1 answer  ·  posted 2y ago by user205‭  ·  last activity 2y ago by Derek Elkins‭

type-theory
75%
+4 −0
How to find a point on a vector equation with another vector equation and perpendicular distance?

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

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

1 answer  ·  posted 4y ago by Prime Mover‭  ·  last activity 2y ago by Derek Elkins‭

abstract-algebra
83%
+8 −0
Does this construction always give a topological vector space?

1 answer  ·  posted 5y ago by celtschk‭  ·  last activity 2y ago by JohnnyJohn‭

topology linear-algebra topological-vector-spaces
66%
+2 −0
Does "shift of terms" in a Faber–Schauder series expansion of f ∈ C[0,1] produce an element of C[0,1]?

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

functional-analysis Banach-space
71%
+3 −0
What is an example of a pathological imbedding of a(n allowed) graph into an oriented surface?

1 answer  ·  posted 2y ago by The Amplitwist‭  ·  last activity 2y ago by The Amplitwist‭

topology graph-theory
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 2y ago by The Amplitwist‭  ·  last activity 2y ago by The Amplitwist‭

topology graph-theory
44%
+2 −3
Cyclical or “loop” fractals?

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

real-analysis fractal
66%
+2 −0
Seeking a theorem about lattices

1 answer  ·  posted 2y ago by WheatWizard‭  ·  last activity 2y 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 2y ago by CrSb0001‭  ·  last activity 2y ago by Lisanne‭

number-theory bases recreational-mathematics
71%
+3 −0
Is it possible to find a solution for any $ae^{bx}+cx+d=0$?

0 answers  ·  posted 2y ago by CrSb0001‭

calculus recreational-mathematics
71%
+3 −0
Is there a $\Delta$-complex structure on the sphere with less than three $0$-simplices?

1 answer  ·  posted 2y ago by The Amplitwist‭  ·  last activity 2y 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 2y ago by Julius H.‭  ·  edited 2y ago by xamidi‭

modal-logic proof-theory hilbert-systems axioms
50%
+4 −4
Defining Bayes’s theorem from scratch in ZFC

1 answer  ·  posted 2y ago by Julius H.‭  ·  last activity 2y ago by xamidi‭

set-theory zfc bayes-theorem
50%
+1 −1
Prove that $\forall x\in\Bbb R:\lfloor x^2\rfloor-\lfloor rx\rfloor\ge-1\iff|r|\le2$.

1 answer  ·  posted 2y ago by TheCodidacter, or rather ACodidacter‭  ·  last activity 2y ago by Derek Elkins‭

inequality solution-verification
71%
+3 −0
Using convexity in the proof of Hölder’s inequality

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

real-analysis
71%
+3 −0
Does {7,4|3} have a realization on the Klein quartic?

0 answers  ·  posted 2y ago by WheatWizard‭

polytopes algebraic-geometry
66%
+2 −0
Find length $MP$ in trapezoid

0 answers  ·  posted 2y ago by TheCodidacter, or rather ACodidacter‭  ·  edited 2y ago by TheCodidacter, or rather ACodidacter‭

geometry
22%
+0 −5
What are the Peano axioms?

1 answer  ·  posted 2y ago by Julius H.‭  ·  last activity 2y ago by rmf‭

logic
66%
+2 −0
The Fourier transform of $1/p^3$

1 answer  ·  posted 2y ago by C-T‭  ·  last activity 2y 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 2y ago by LL 3.14‭  ·  edited 2y 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 2y ago by Julius H.‭  ·  last activity 2y ago by Dan Doel‭

logic
40%
+0 −1
What is a one-variable fragment of first-order logic?

0 answers  ·  posted 2y ago by Julius H.‭

logic
66%
+2 −0
matrix inverse of $I + A$ where $A$ is skew-symmetric

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

linear-algebra
42%
+1 −2
Explain derived categories to someone without a strong background in homological algebra [closed]

0 answers  ·  posted 2y ago by Julius H.‭  ·  closed 2y ago by Peter Taylor‭

category-theory
28%
+0 −3
What is a dual object? [closed]

0 answers  ·  posted 2y ago by Julius H.‭  ·  closed 2y ago by Peter Taylor‭

category-theory
66%
+4 −1
is arithmetic finitely consistent?

0 answers  ·  posted 2y ago by Jason‭

proof logic peano-arithmetic incompletness consistency
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