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What is the Asymptotic Order of the Sum of Random Variables with non-finite Moments?
I showed that every Gram matrix, i.e. a $n \times n$ matrix $A$ with $A_{ij} = \langle x_i,x_j\rangle$ where $x_1,...,x_n$ are vectors in an inner product vector space $V$, is Hermitian and positive semi-definite. But how to show the converse: For every Hermitian positive semi-definite matrix there is a inner prod...
Past research on matrix subalgebras generated by a given set of generators has one major restriction: most of the literature on the generation of algebras automatically presumes unitality of the generator set, meaning that most proofs are based on the implicit assumption of a unit element among the given matrices; this...
To be honest I dont know how to do this problem, I only know that we should get a second order linear differention equation for the position $x$. And we have to solve the problem using theta. I know that $X(t)= r\sin\theta$, where r would be the length of the rod but I dont know where to go from there. Were also gi...
[Green's theorem](https://en.wikipedia.org/wiki/Green%27s_theorem) says that: $$ \int_C L \ dx + \int_C M \ dy = \iint_D \frac{\partial M}{\partial x} - \frac{\partial L}{\partial y} \ dx \ dy $$ If the M and N statisfy $\frac{\partial M}{\partial x} - \frac{\partial L}{\partial y} = 1$, then the formula can be use...
If a series $\sum u_n$ converges, $u_n \to 0$ but is there any type of condition on $u_n$ that would ensure that $nu_n \to 0$? I can think of many $u_n's$ satisfying this, all geometric series terms, p-series terms too for $p\geq 2$, so maybe there's a general condition on $u_n$ that along with $\sum u_n < \infty$ g...
If a series $\sum u_n$ converges, can anything be said about $nu_n$?
Suppose we want to formalise some parts of mathematics within set theory, which is itself formalised in a first-order language (in the standard way). Logic is assumed to be classical. In particular, this means that – at the level of semantics – every term must have a denotation, which in turn means that every function ...
Suppose we have $A,B \in \operatorname{Mat}(n, \mathbb{R})$, and let $\alpha(A,B) = \text{Tr}(AB)$ and $\beta(A,B) = \text{Tr}(AB^T)$. Then is it possible to show that both $\alpha$ and $\beta$ cannot be bilinear forms? If not then what can be shown as a counter-example? Furthermore, how can I show that only $\beta$...
I am reading an interesting paper [One of the numbers ζ(5), ζ(7), ζ(9), ζ(11) is irrational](https://www.mathnet.ru/php/archive.phtml?wshow=paper&jrnid=rm&paperid=427&option_lang=eng) by Zudilin. We fix odd numbers $q$ and $r$, $q\geq r+4$ and a tuple $\eta_0,\eta_1,...,\eta_q$ of positive integer parameters satisfying...
Consider $n$ equally sized circles $c_i$ in the plane with their centers $x_i$ in the vertices $v_i$ of a regular $n$-gon and all meeting in the center of that $n$-gon. Examples: - Fig. 1: circle pattern for $n=5$: [![enter image description here][2]][2] - Fig 2: circle pattern for $n=15$: [![enter i...
I have the following problem: Consider complex Euclidean spaces H and H′ such that $dim(H) ⩽ dim(H′)$. Let ${|v_i⟩}^{k}_{i=1} ⊂ H$ and ${|w_i⟩}^{k}_{i=1} ⊂ H′$ denote orthonormal sets of vectors. Show that there exists an isometry $V : H → H′$such that $V |v_i⟩ = |w_i⟩$ for all i ∈ {1,. . . , k}. I know that...
I am reading David Zywina's ["Elliptic curves with maximal Galois action"][1]. For a number field $K$, he defines $\mathbb{Q}^{\text{cyc}} \subset \overline{K}$ to be "the" cyclotomic extension of $\mathbb{Q}$. 1. Is $\mathbb{Q}^{\text{cyc}}$ the minimal cyclotomic extension corresponding to the conductor of $K$ o...
Why is $K \cap \mathbb{Q}^{\text{cyc}}=\mathbb{Q}$ iff $\chi_K(G_K)=\hat{\mathbb{Z}}^{\times}$?
Suppose we have a Compound Poisson Process with intensity $\lambda$ $$ S_t = \sum_{i=1}^{N_t} X_i. $$ We can compute the formula for the CDF as follows \begin{align*} F_{S_t}(x) = P(S_t \leq x) &= \sum_{k=0}^\infty P(S_t \leq x \mid N_t = k)P(N_t = k) \\ & = \sum_{k=0}^\...
### Showing that $(e^{\lambda B_t - \frac{1}{2}\lambda^2t})_{t\geq 0}$ is a $\mathbb{R}$-valued martingale Let $B$ be a standard $\mathbb{R}$-valued Brownian motion and let $\lambda\in\mathbb{R}$. From $B_t-B_s$ being independent of $\mathcal{F}_s$ and $B_t-B_s \sim \mathcal{N}\left(0, t-s\right)$ follows $\math...
Is $(e^{i \lambda B_t - \frac{1}{2}\lambda^2t})_{t\geq 0}$ a martingale?
I am trying to extract the mathematical expression of creating a set of elements from the diagonal of a matrix, but after filtering by a vector. For example: Be X a matrix of N x N elements, v a vector of N elements, and R the result of N elements: $A = \begin{bmatrix} 1 & 0 & 1 \\ 0 & 1 & 1 \\ 0 & 0 & 0 \end{bm...
I have somewhat often found myself in the following situation, especially when self-studying a mathematical subject: I'm reading a book on a certain topic, and at certain parts I don't immediately understand something, for example a proof. But instead of re-reading it I just skip over it and continue. This then lead...
In the book, a first course in functional analysis by D.Somasundaram, it is mentioned that $\sigma(x) = \{z \in\mathbb{C}: \vert z\vert\leq\Vert x \Vert\}$ But the proof is given only for one side inclusion..that is., The spectrum of an element x in a Complex Banach Algebra is a subset of the closed disk with cent...
Is the spectrum of an element in an algebra ,$\sigma(x) = \{z \in\mathbb{C}: \vert z\vert\leq\Vert x \Vert\}$?
Past research on matrix subalgebras generated by a given set of generators has one major restriction: most of the literature on the generation of algebras automatically presumes unitality of the generator set, meaning that most proofs are based on the implicit assumption of a unit element among the given matrices; this...
I was reading Rotman's "An Introduction to the theory of Groups" Chapter 12 "The Word Problem". I cannot understand the key concepts of Turing Machines and undecidibilty. I want to prove understand the proof "There exists a finitely presented group which has unsolvable word problem". Can anyone point out any beginner f...
Is the spectrum of an element in an algebra, $\sigma(x) = \{z \in\mathbb{C}: \vert z\vert\leq\Vert x \Vert\}$?
I was reading Section 1.5 of *Sheaves on Manifolds* by Kashiwara and Shapira. In the proof of Propositon 1.5.6, they states that in order to prove the functor $H^0:K(\mathcal{C})\rightarrow \mathcal{C}$ is a cohomological functor, where $\mathcal{C}$ is an abelian category, it suffices to prove that $H^0(Y)\rightarrow ...
### Showing that $(e^{\lambda B_t - \frac{1}{2}\lambda^2t})_{t\geq 0}$ is a $\mathbb{R}$-valued martingale Let $B$ be a standard $\mathbb{R}$-valued Brownian motion and let $\lambda\in\mathbb{R}$. From $B_t-B_s$ being independent of $\mathcal{F}_s$ and $B_t-B_s \sim \mathcal{N}\left(0, t-s\right)$ follows $\math...
Is $(e^{i \lambda B_t + \frac{1}{2}\lambda^2t})_{t\geq 0}$ a martingale?
In his *Mathematical Methods of Classical Mechanics*, V.I. Arnold states the following theorem without proof in pages 75-76: > Let $\gamma$ be a smooth plane curve, and let $q_1, q_2$ be local coordinates where $q_1$ parameterises the curve and $q_2$ is the coordinate in the orthogonal direction to the curve. Consi...
Assume that $X\in \mathrm{PSD}(n)$ is a symmetric, positive semi-definite matrix with real entries and $C>0$ is a positive real number. If $X$ satisfies $$ \forall \alpha\in\mathbb{Z}^n\setminus\{0\},\qquad \alpha^T X \alpha \geq C, $$ then is it true that $X$ is positive definite? That is, if $X$ is lower bounded on...
Can a continuous function $f:\mathbb{R}^2\to\mathbb{R}$ be constant on the following hyperbolas? $$H_a=\{(x,y)\in\mathbb{R}^2:x+1/y=a\},a\in\mathbb{R}$$ $$H_\infty=\mathbb{R}\times\{0\}$$ That is, such that $\forall a\in\mathbb{R}\cup\{\infty\}:P_1,P_2\in H_a\Rightarrow f(P_1)=f(P_2)$. I know that, if this were the ...
Can a continuous function be constant on these hyperbolas?
I am trying to extract the mathematical expression of creating a set of elements from the diagonal of a matrix, but after filtering by a vector. For example: Let $A$ be a $3 \times 3$ matrix, $\mathbf{v}$ a $3 \times 1$ vector, and $\mathbf{R}$ be the resulting $3 \times 1$ vector: $A = \begin{bmatrix} 1 & 0 & 1...
Lets say there is a curve whose curvature is given as k = 0.01. What i want to calculate is angle between tangent drawn at point "P" which is at a distance of "X" along the curve and Y axis (shown as θ in pic) . [![enter image description here][1]][1] [1]: https://i.stack.imgur.com/CTt1d.jpg Can any relation...
If f”(a) is defined, is f differentiable near a? My logic goes, if f”(a) exist, then f’(a) must be defined near a, thus f is differentiable near a. Is that correct?
Is the function differentiable near a point?
I am going through some lecture notes in commutative algebra. I am struggling with one basic example which I want to understand fully before going further. The example is the following: We take $\mathbb{C}$-module $\mathbb{C}^n.$ We restrict scalars to $\mathbb{R}$ and obtain $\mathbb{R}^{2n}.$ Then we extend scalar...
Can a non-constant continuous function $f:\mathbb{R}^2\to\mathbb{R}$ be constant on the following hyperbolas? $$H_a=\{(x,y)\in\mathbb{R}^2:x+1/y=a\},a\in\mathbb{R}$$ $$H_\infty=\mathbb{R}\times\{0\}$$ That is, such that $\forall a\in\mathbb{R}\cup\{\infty\}:P_1,P_2\in H_a\Rightarrow f(P_1)=f(P_2)$. I know that, if t...
Can a non-constant continuous function be constant on these hyperbolas?
If $f’’(a)$ is defined, is $f$ differentiable near $a$? My logic goes, if $f’’(a)$ exist, then $f’(a)$ must be defined near $a$, thus $f$ is differentiable near $a$. Is that correct?
I am learning about Havel Hakimi. I know how the algorithm works, but I'm not sure what happens when there are no enough numbers. For example, (2,3,3,4). I remove 4, then I'm supposed to subtract 1 from the next 4 numbers ın the sequence but there only 3 numbers. Does that mean it's not graphical, or should I subtract ...
Havel Hakimi Theorem -- What happens if there are no enough numbers?
I'm looking for a pairing function $f(x,y)$ which gives unique values for every combination of integers $x,y>0$ and 0 for $x=0$ $\forall y$.<br> Or to be more general we can also replace $0$ with constants. <br> - We do know the max values of $x$ and $y$ can achieve - We are allowed to shift $x, y$ values. So we al...
Can we find any (better) pairing function $f(x,y)$ with $f(0,y)=0$? Does it help if we do know min/max values of $x,y$?
Is this method for constructing nilpotent matrices effective?
I only need help with the last part of the following question: >Let $U(\rho, \tau, \lambda)$ and $V(\rho, \tau, \lambda)$ be matrix-valued functions. Consider the following system of overdetermined linear partial differential equations: $$ \frac{\partial}{\partial \rho} \psi=U \psi, \quad \frac{\partial}{\partial ...
Consider the following two expressions in $\tan{x}$: $\sqrt[3]{\tan x+1}$ $\sqrt[3]{\left(\tan x\right)^{3}+\left(\tan x\right)^{2}-\tan x-1}$? There are trigonometric identities which can be used to express a compound angle as a polynomial in $\tan{x}$, for example $\tan{3x}=\frac{3\tan{x}-\tan^{3}{x}}{1-3...
If I start with a set of consecutive primes, let's say {2,3,5,7}. Now I assume as in euclids theorem that these are all primes. By the proof I get 2*3*5*7 + 1 = 211. 211 is prime, so I add it to the set: {2,3,5,7,211}. If the resulting number is not prime, add the prime dividers of this number which are not in the set....
Does euclids proof of infinite primes generate them all if you add the new prime to the list?
[This question][1] discusses how $\mathrm{S}L(2,\mathbb{R}$) coincides with $\pm\exp(z)$ with $z\in \frak{sl}(n,\mathbb{R}$) (the real traceless matrices). Is it known what happens for $n>2$? Namely, one can represent all invertible matrices with determinant $1$ and trace greater than or equal to $-2$. Also, just b...
What is in the image of the exponential of $\frak{sl}(n,\mathbb{R}$)? What do you need to get all of $\mathrm{SL}(n,\mathbb{R}$)?
If I start with a set of consecutive primes, let's say $\{2,3,5,7\}$. Consider $2\times 3\times5\times7+ 1 = 211$. Now, $211$ is prime, so I add it to the set: $\{2,3,5,7,211\}$. If the resulting number is not prime, add the prime divisors of this number which are not in the set. Just out of curiosity, does this ge...
Does euclid's proof of infinitude of primes generate all the primes if you keep adding the new primes to the list?
Let $A$ be a finitely generated algebra over some field $k$, and assume that $A$ is an integral domain. By Noether normalization, we have a finite injective ring homomorphism $\varphi: k[x_1, \ldots, x_n] \hookrightarrow A$. **Is $A$ always a free module over $k[x_1, \ldots, x_n]$?** I know that this fails for a...
Consider a probability distribution on the set of all ordered binary strings of length $M$. Each element may then be written as $( s_1, s_2, \cdots, s_M )$ with each $s_k \in \{ 0, 1\}$ and the probability distribution is a non-negative function $p(\{s_k\})$ which sums to $1$. Just by parameter counting, the probab...
Can you obtain the probability distribution on a finite discrete space through its moments? If so, how?
I'm looking for a pairing function $f(x,y)$ which gives unique values for every combination of integers $x,y>0$ and 0 for $x=0$ $\forall y$.<br> Or to be more general we can also replace $0$ with constants. <br> - We do know the max values of $x$ and $y$ can achieve - We are allowed to shift $x, y$ values. So we al...
Let's call an *algebraic invariant* (under the action of $\text{GL}(\mathbb{R}^n)$) of a tensor of order $N$ to an algebraic combination of the components of that tensor. In other words, a homogeneous polynomial in the components of the tensor. * For $N = 2$ algebraic invariants are well known: given a second-order t...
As a hint, remember that big-O is *not* a tight bound. Could you make $r(n)$ grow much more rapidly than $g(n)$, such that $O\left( \frac{s(n)}{r(n)}\right)$ ends up being much smaller than $\frac{f(n)}{g(n)}$? Hope this helps!
I am a bit new to functional analysis and I stumbled upon this problem that confuses me. Consider the space $X$ of bounded, non-decreasing, right-continuous functionals $F$ on $[0,1]$. Specifically, the space of cumulative distribution functions on $[0,1]$ is a subset of $X$. I have a continuous linear functional $\...
Riesz representation theorem with Stieltjes integral?
Image 1 is the textbook question and image 2 is the graph in question. [1]: https://i.stack.imgur.com/DZV8Z.jpg [2]: https://i.stack.imgur.com/5Y9XE.jpg The answer key says that the domain is all real numbers. I thought that the domain is actually -2<x<2. My question is, is the answer key incorrect in thi...
Consider a sequence of holomorphic function $\{f_n\}$ on a domain $D$ with limit function $f$ . It is known that if the convergence is compact (i.e. converge uniformly to $f$ in every compact subset of $D$), $f$ is holomorphic on $D$. Then is there an example that $f$ is holomorphic on $D$ but the convergence is n...
Image 1 is the textbook question and image 2 is the graph in question. [1]: https://i.stack.imgur.com/DZV8Z.jpg [2]: https://i.stack.imgur.com/5Y9XE.jpg The answer key says that the domain is all real numbers. I thought that the domain is actually -2<x<2. My question is, is the answer key incorrect in t...
Image 1 is the textbook question and image 2 is the graph in question. [![enter image description here][1]][1] [![enter image description here][2]][2] The answer key says that the domain is all real numbers. I thought that the domain is actually -2<x<2. My question is, is the answer key incorrect in this ca...
Image 1 is the textbook question and image 2 is the graph in question. [![enter image description here][1]][1] [![enter image description here][2]][2] The answer key says that the domain is all real numbers. I thought that the domain is actually -2<x<2. My question is, is the answer key incorrect in this ca...
Image 1 is the textbook question and image 2 is the graph in question. The answer key says that the domain is all real numbers. I thought that the domain is actually -2<x<2. My question is, is the answer key incorrect in this case or am I wrong? I'm new to learning math as a hobby and I don't have anyone who can ...
How do you evaluate the following integrals? 1. $\int f df$ 2. $\int f' df$ 3. $\int f'' df$ Where $f(x)$ is a function of x, and $f', f''$ are the first and second derivatives with respect to x. Regarding integral 1, I think that the answer is: $(1/2)f^2$. But I get stack with the other two.
How to integrate a function or its derivatives with respect to itself?
Let $(X_t)_{t\ge0}$ be a time-homogeneous Markov process with transition semigroup $(\kappa_t)_{t\ge0}$ and $\tau$ be a finite stopping time adapted to $(X_t)_{t\ge0}$. Say I run the following algorithm: [![enter image description here][1]][1] Say my abort criterion ensures that $\sum_{i=0}^{n-1}\tau_i$ is a samp...
How do we get an estimator for $\operatorname E\left[\int_0^\tau f(X_t)\:{\rm d}t\right]$?
Image 1 is the textbook question and image 2 is the graph in question. [![enter image description here][1]][1] [![enter image description here][2]][2] The answer key says that the domain is all real numbers. I thought that the domain is actually -2<x<2. My question is, is the answer key incorrect in this ca...
I'm reading Emily Riehl's *Category Theory in Context* and pondering Exercise 1.2.i, where the author writes "Defining $\mathcal{C}/c$ to be $(c/\mathcal{C}^{op})^{op}$," in an effort to exhibit duality between the slice and co-slice categories. If you allow yourself complete freedom to just "reverse all the arrows" i...
When performing the "opposite" operation in a category, can you reverse arrows that are part of an object's definition?
[nonlinear differential equation][1] Is it possible to obtain below result by considering z(0)=0? [result][2] [1]: https://i.stack.imgur.com/1a5gV.png [2]: https://i.stack.imgur.com/t4Py6.png
What kind of nonlinear differantial equation is this?
Consider a sequence of holomorphic function $\{f_n\}$ on a domain $D$ with limit function $f$ . It is known that if the convergence is compact (i.e. converge uniformly to $f$ in every compact subset of $D$), $f$ is holomorphic on $D$. Then is there an example that $f$ is holomorphic on $D$ but the convergence is n...
Ross and Pekoz's book A Second Course in Probability gives the following question in their chapter on Stein-Chen Method: Compute a bound on the accuracy of a normal approximation for a Poisson random variable with mean 100. I believe this post was seeking help on the same question, but never found it https://math...
Here is one way. Since $3x+2y+z=x+(x+y)+(x+y+z)$, the problem is transformed to find how many positive solutions for $a+b+c=2021$ such that $0<a<b<c$. Without any restriction, there are $2020\choose 2$ positive solutions. Since 2021 is not divisible by 3, it is impossible to have $a=b=c$. Now consider the cases of ...
What kind of nonlinear differential equation is this?
Consider a sequence of holomorphic function $\{f_n\}$ on a domain $D$ with limit function $f$ . It is known that if the convergence is compact (i.e. converge uniformly to $f$ in every compact subset of $D$), $f$ is holomorphic on $D$. Then is there an example that $f$ is holomorphic on $D$ but the convergence is n...
The problem is to maximize $(x-y)^2(y-z)^2(z-x)^2$ where $x^2+y^2+z^2=1$. Since the domain is compact and the function is continuous, it is certain that extrema must exist. Plus I figured out that the maximum is $1/2$ where $(x,y,z) = (1/\sqrt{2}, 1/\sqrt{2}, 0)$ by Lagrange multiplier. However, the calculatio...
The problem is to maximize $(x-y)^2(y-z)^2(z-x)^2$ over all $(x,y,z)\in \mathbb{R}^3$ satisfying $x^2+y^2+z^2=1$. Since the domain is compact and the function is continuous, it is certain that extrema must exist. Plus I figured out that the maximum is $\frac{1}{2}$ where $(x,y,z) = (\frac{1}{\sqrt{2}}, \frac{1}{\...
> Let $Q_c(x)=x^2+c$. Prove that if $c<\frac14$, there is a unique > $\mu>1$ such that $Q_c$ is topologically conjugate to > $F_\mu(x)=\mu(1-x)$ via a map of the form $h(x)=\alpha x+\beta$. Interpretation: $h(x)$ is a linear map. $Q_c(x)$ and $F_\mu(x)$ are a quadratic maps. The claims is that if $c<\frac14$, then...
Let $k$ be a local field, and consider the local ring of the formal power series $k[[x_1, \cdots, x_n]]$. Consider the field of fraction $k((x_1,\cdots, x_n)):=\text{Frac}(K[[x_1, \cdots, x_n]])$. It is not a local field, but we can define a discrete valuation for it. I am interested in automorphisms of $k((x...
Is there any substantial study regarding the automorphism of the field $k((x_1,\cdots, x_n)):=\text{Frac}(k[[x_1, \cdots, x_n]])$?
Recently I meet a very complex integral and wonder whether there is an analytic solution or an approximate expression to this integral? The expression is as follows: $$ \mathcal{Z}^{l}_{n}(r, x)=\int_{0}^{\infty}exp(-\frac{R^2}{W^2}) I_{n}(\frac{BxR}{W^2}) J_{n+l}(rR) RdR$$ where $B$ and $W$ are constants. $J_n$ $I_n...
Is there an analytic solution or approximate expression to this integral?
Is it useful to define the derivative as $\lim \limits_{h\to 0} \frac{f(x+h)-f(x-h)}{2h}$?
> Let $Q_c(x)=x^2+c$. Prove that if $c<\frac14$, there is a unique > $\mu>1$ such that $Q_c$ is topologically conjugate to > $F_\mu(x)=\mu(1-x)$ via a map of the form $h(x)=\alpha x+\beta$. Interpretation: $h(x)$ is a linear map. $Q_c(x)$ and $F_\mu(x)$ are a quadratic maps. The claims is that if $c<\frac14$, then...
In this >answer to [Is there any valid complex or just real solution to $\sin(x)^{\cos(x)} = 2$?](https://math.stackexchange.com/a/4693242/905886), one must calculate $$\frac{d^{n-1}}{dw^{n-1}}\left.\frac{4^{-\frac{n}{\sqrt w}}}{\sqrt w}\right|_1=\sum_{m=0}^\infty\frac{\Gamma\left(\frac12-\frac m2\right)(-\ln(4)...
In order to calculate the Fourier transform of a formula as follow: $$F(x, y) = exp(-\frac{(x-x_0)^2 + (y-y_0)^2}{W^2})e^{-iltan^{-1}(\frac{y}{x})} $$ Where $B$ and $l$ are constants. After transform this formula into cylindrical coordinate system I meet a very complex integral and wonder whether there is an analytic ...
**Does there exist two binary operations + and ∗ on {0,1} such that + and ∗ satisfy the same equations, but not the same quasi-equations? If not, are there such binary operations on a finite set of higher cardinality, and if so, what is the smallest possible cardinality?**<p> (Partial) answers:<p> <ol> <li> No, ...
Let $k,n\in\mathbb{N}$. Let $N(k,n)$ denote the size of the finite set $$\{(x_1,\cdots,x_k)\in\mathbb{N}^k:x_1+2x_2+\cdots+kx_k=n\}. $$ I feel it special and important. Do $N(k,n)$ have names? Is there a table of values?
In this >answer to [Is there any valid complex or just real solution to $\sin(x)^{\cos(x)} = 2$?](https://math.stackexchange.com/a/4693242/905886), one must calculate $$\frac{d^{n-1}}{dw^{n-1}}\left.\frac{4^{-\frac{n}{\sqrt w}}}{\sqrt w}\right|_1=\sum_{m=0}^\infty\frac{\Gamma\left(\frac12-\frac m2\right)(-\ln(4)...
Let $G$ be a reductive algebraic group over the field $\mathbb C$, $B\subset G$ a Borel subgroup and $G/B$ their quotient variety. For every $B$-module $(M,\rho)$ we can construct the associated $G$-equivariant vector bundle $G\times^BM\to G/B$, where $G\times^BM$ is the quotient of $G\times M$ by the relation $(g,...
<h4>Question Summary (to Make Easier to Reference in the Answer)</h4> $$ \text{If }x^2-16\sqrt{x}=12 \text{ what is the value of }f=x-2\sqrt{x} \tag{Eq. 1}$$ <h4>Checking for Consistency by Plugging in the $f=x-2\sqrt{x}=2$</h4> Check $ x - 2\sqrt{x}-2=0$ implies $(\sqrt{x}-1)^2=2+1=3$ so $\sqrt{x}=1+\sqrt{3...
Antisymmetric, or skew-symmetric tensors on a subset of indices are those that get multiplied by $-1$ when any of the indices from the subset are transposed. This type of tensor is widely used in physics and mathematics. Now imagine I have, say, a tensor of type $(3, 0)$ that gets multiplied by $e^{2\pi i\over3}$ wh...
Does this type of tensor appear anywhere?
How many functions such that the Image is a partition?
In order to calculate the Fourier transform of a formula as follow: $$F(x, y) = \exp\left(-\frac{(x-x_0)^2 + (y-y_0)^2}{W^2}\right)e^{-il\tan^{-1}(\frac{y}{x})} $$ Where $B$ and $l$ are constants. After transform this formula into cylindrical coordinate system I meet a very complex integral and wonder whether there is...