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5:39 AM
The tag was mentioned, for example, here and a few other times.
1 message moved to ­Trash
The oldest occurrences found by those queries are from 2017:
Q: Derivations of central extensions of simple Lie algebras

Salvatore SicilianoLet $L$ be a finite-dimensional Lie algebra over a field of characteristic zero. It is not difficult to see (and also follows from Theorem 4.4 of [G. Hochschild: Semi-simple algebras and generalized derivations, Amer. J. Math. 64, (1942), 677–694]) that the derivation algebra $D(L)$ of $L$ is sim...

Q: The limitation of derivation of modified Bessel function of second kind

user108207The final result I draw is related to the integral of modified Bessel function of the second kind. But I can not solve it, and I need a explicit solution Are you willing to help me? Thank all $I = \mathop {\lim }\limits_{x \to 0} \frac{\partial }{{\partial x}}\frac{{{K_0}(a\sqrt x )}}{{{K_0}(b\s...

Q: Formal Cauchy-Riemann equations for formal power series without complex analysis

M.G.Consider the ring $\mathbb{C}[[X,Y]]$ and its subring $\mathbb{C}[[X+iY]]$, where $i=\sqrt{-1}$. One can show that $f(X,Y):=u(X,Y)+iv(X,Y)\in \mathbb{C}[[X,Y]]$ lies in $\mathbb{C}[[X+iY]]$ iff $u$ and $v$ satisfy the CR-equations formally. The necessary condition follows by straightforward forma...

This question from May 2017 had this tag, but it was removed: Random graphs- Erdos and Renyi 1959 paper.
In mathematics, a derivation is a function on an algebra which generalizes certain features of the derivative operator. Specifically, given an algebra A over a ring or a field K, a K-derivation is a K-linear map D : A → A that satisfies Leibniz's law: D ( a b ) = a D ( b ) + D ( a ) b . {\displaystyle D(ab)=aD(b)+D(a)b.} More generally, if M is an A-bimodule, a K-linear map D : A → M that satisfies the Leibniz law is also...
On Mathematics, the tag derivations has only 8 questions. At the moment, it doesn't have a tag-info, either.
A snapshot of the tag in the Wayback Machine from May 2021.
6:08 AM
At the moment, there are 78 questions tagged .
I see that the OP edited this question, so that might have lead to the question on meta: Derivative of $X \mapsto X X^T$
Q: Derivative of $X \mapsto X X^T$

Mattyred99My goal is to compute this derivative: $$ \frac{d(LL^T)}{dL} $$ Where $L$ is a lower triangular matrix obtained from a Cholesky decomposition. Is there a way to compute it in a compact form?

The question currently has 4 close votes and is in the close votes review.
3 hours later…
9:16 AM
Jun 3, 2018 at 8:26, by Martin Sleziak
What is the intended meaning of tag . Shouldn't it be either removed or replaced by in the questions that are actually about derivatives? Such as: Partial derivatives of spherical harmonics and Derivative with multiple summation operators.
Nov 30, 2018 at 8:00, by Martin Sleziak
It's quite likely that the question is going to be closed and deleted. But it is at least an opportunity to remind that the tag derivations has a bit unclear usage. Is it suitable here: Does $f \leq f'$ imply $f' \leq f''$?
5 hours later…
2:23 PM
My old algebra memory says: a derivation on a ring $R$ is a map $D : R \to R$ satisfying $D(a+b) = D(a) + D(b)$ and $D(ab) = aD(b)+D(a)b$. Perhaps that is what the tag is for. — Gerald Edgar 1 hour ago
@GeraldEdgar My concern is that some people might use it for questions on derivatives, i.e., as a synonym for differentiation — Rodrigo de Azevedo 1 hour ago
For example, there are 7 questions tagged derivations+real-analysis.
Q: Prove a $C^{\infty}$ multivariable function is lipchitz via Jacobian matrix

SC_thesardI would like to prove a real $C^{\infty}$(polynomial) multivariable function $F : (a_1,a_2,...a_n) \rightarrow (b_1,b_2,...b_n) $ is lipchitz of parameter $l$ is it sufficient to prove the norm of dominant eigenvalue of $Jacobian(F)$ is less than $l$. In other words, is the "spectral radius of ...

Q: Does every real function have this weak derivation property?

DattierAfter this question : Does every real function have this weak continuity property? Natrualy there are an other (more difficult) : Is it true that for every real function $f:\mathbb{R}\to\mathbb{R}$, there exists a real sequence $(x_n)_n$, taking values different from $c$, converging to some...

Q: "Insanely increasing" $C^\infty$ function with upper bound

Dominic van der ZypenLet $C^\infty$ denote the collection of functions $f:\mathbb{R}\to\mathbb{R}$ such that for every positive integer $n$, the $n$-th derivative of $f$ exists. For $f\in C^\infty$ we set $f^{(0)} = f$, and $f^{(n+1)} = \big(f^{(n)}\big)'$ for all non-negative integers $n$. Is there $f\in C^\inft...

Q: Why this function is monotonic?

MigalobeLet $a> 0, \alpha<0$ and $\beta>0$. How to prove that the function: $$f(x)=\frac{(\Gamma(a)-\Gamma(a,\alpha \ln(\beta x))) (\alpha\ln(x))^a}{(\alpha\ln(\beta x))^a (\Gamma(a)-\Gamma(a,\alpha \ln(x)))},$$ is monotonic. I tried the sign of derivative but is more delicate.

Q: A question on fractional derivatives

user168611I know practically nothing about fractional calculus so I apologize in advance if the following is a silly question. I already tried on math.stackexchange. I just wanted to ask if there is a notion of fractional derivative that is linear and satisfy the following property $D^u((f)^n) = \alpha D^u...

Q: Prove or disprove: A differentiable function $f$ is always non-negative with this condition

user173434I want to prove that a differentiable function $f: [0,\infty) \rightarrow \mathbb{R} $, which satisfies the following condition is always non-negative: Assume $f(0)=0$ and whenever $f(a)=0$, then $f'(a) \geq 0$ and $f''(a) \neq 0$. Note that if I change the condition to this: $f(0)=0$ and whenev...

Q: Subdifferential of a convex function admits a continuous selection

AimarLet $F$ be a continuous convex function on $\mathbb{R}^n$. If the subdifferential $\partial F(x)$ of $F(x)$ admits a continuous selection, for every $x \in \mathbb{R}^n$, does it mean that $F$ is differentiable on $ \mathbb{R}^n$ ? I was trying to use theorem 25.5 and 25.6 (Rockafellar: Convex An...

2 hours later…
4:16 PM
I could also see it getting used for questions about logical derivations, i.e. formal proofs in the sense of natural deduction or similar systems. — Peter LeFanu Lumsdaine 2 hours ago

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