# All Questions

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### Books on First Hitting times

I am looking for books or expositional papers on First hitting times of sets by Brownian motion (any dimension). Here are some that are devoted to this subject or contain sections on it: 1)Sidney ...
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### Generators of the algebra of invariant polynomials on a Lie algebra and the root-space decomposition

Let $G$ be a connected, simply-connected complex semisimple group with Lie algebra $\mathfrak{g}$. Fix a pair $T\subseteq B\subseteq G$ of a maximal torus and Borel subgroup, and let $\mathfrak{t}$ ...
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### How many isolated roots can a polynomial in $z$ and $\overline{z}$ have?

This is probably well-known by I can't find it now online. My guess is that if the degree is $n$ then it's $2n$ but it's just a hunch. EDIT: This is an edited version. Before I asked about roots ...
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### question related to kernel methods [on hold]

i have some questions related to kernel methods in Machine Learning,hope someone can give proves. K(x,y) is kernel iff 1.K is symmetric 2.K is positive definite. ...
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### Meaning of eigenvalue 1 and symmetry in Laplacian spectra of graphs

We often see normalized Laplacian spectra of graphs where density on eigenvalue 1 serves as an axis of symmetry, with particularly high (blue spectra in the figure) or low densities (red spectrum) ...
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### state-of-the-art graph theory libraries like LEDA

I came across LEDA (library of efficient data types and algorithms) which implements graph theory algorithms: http://www3.cs.stonybrook.edu/~algorith/implement/LEDA/implement.shtml I want to ask: ...
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### The zeta function and classical mechanics

In this paper, Guilherme França and André LeClair show that $$\gamma\sim 2 \pi \left(y-11/8\right)/W\left((y-11/8)e^{-1}\right)$$ where $W$ is the Lambert W function, and $\gamma$ are imaginary parts ...
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### Using Excel's NormInv and Proportion Estimates for Monte Carlo [on hold]

I have some data. Here's an example (ogive) 517 625 813 855 966 1143 1227 1248 1343 1367 1461 1465 1572 1574 1738 I can derive a % based on frequency of the value 0 0.071428571 0.142857143 ...
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### Effective version of the Bombieri-Vinogradov theorem

Is there an effective version of the Bombieri-Vinogradov Theorem, in that have bounds on the implied constant been found?
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### Is this inequality true?

Let $\Omega$ be a bounded domain with smooth boundary. Let $$S=\{u\in C^2(\overline \Omega): \frac{\partial u}{\partial n}=0 \text{ on } \partial\Omega \}.$$ Fix $\Phi\in S$ with $\Phi(x)>0$ for ...
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### A (different) foliation arising from Hopf fibration

In this question, first we fix an isomorphism between $TS^{3}$ and $S^{3}\times \mathbb{R}^{3}$.(To be more precise we consider the global trivialization of $TS^{3}$ with help of $3$ global ...
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### Is there a simple proof that Milnor $K_2$ of a number field is torsion?

This is a theorem of Garland. I had a look at the original paper which looks pretty complicated. I was wondering if the proof has been simplified over the years or if a different approach is nowadays ...
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### Can the Gaussian integers be covered by restricted recurrences?

Relaxation of the second question here. Let $a(n)$ be recurrence of the form $a(n)=f(n,a(n-1)\ldots(a(n-k))$ with fixed initial terms. (Observe that it might depend on $n$). $f$ may contain ...
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### Fano varieties of cubic threefolds

Let $X$ be a smooth cubic threefold over $\mathbb{C}$. Let $F(X)$ denote the Fano variety of lines in $X$, which is a smooth surface of general type. Is this class of surfaces distingushed ...
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### The Riemann Zeta Function Works [on hold]

1 - Any counterexamples known for the Riemann Zeta Function? 2 - How to generalize the following? Here we have the visualization of the Riemann Zeta Function 3D Plot and the plane. We can observe ...
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### Can this specific Mixed-Integer Linear Program constraint be expressed? [on hold]

Thanks for your time. I have a linear program and no idea how I could express a form of constraint and even if it's possible. Maybe someone here know a solution. A company assembly and sells a ...
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### The number of blocks in Szemerédi Regularity Lemma

In mathematics, the Szemerédi regularity lemma states that every large enough graph can be divided into subsets of about the same size so that the edges between different subsets behave almost ...
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### Resolving nodes of a quintic CY 3-fold

Let's consider the following quintic 3-fold $X$: $$\{(x_i) \in \mathbb{P}^4 \ | \ x_1f(x)-x_2g(x)=0\}$$ for generic homogeneous polynomials $f(x),g(x)$ of degree four. It ...
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### Understanding Prof. Keevash's proof on the “Existence of Designs” [on hold]

I have tried to read Prof. Kevvash's paper on the "Existence of designs". I am finding it very tough to read it linearly. I am comfortable with the nibble ideas and probabilistic methods in general. ...
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### the eigenvalues of a generalized circulant matrix

A $2k\times 2k$ circulant matrix $\ C$ takes the form \begin{align} C= \begin{bmatrix} c_0 & c_{2k-1} & \dots & c_{2} & c_{1} \\ c_{1} & c_0 & c_{2k-1} & & c_{2} ...
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### Behavior of elementary symmetric polynomials near zero sets

It is straightforward to show (see Characterizing intersection of zero sets of elementary symmetric polynomials on R^n) that the set of points $\Lambda_{k}$ in $x \in \mathbb{R}^{n}$ with ...
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### Compare time it takes to travel a curve and a line [on hold]

First posted in Math Stack Exchange: http://math.stackexchange.com/questions/989690/compare-time-it-takes-to-travel-a-curve-and-a-line?noredirect=1#comment2025799_989690 Suppose you have a right ...
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### Polynomial recurrence relation covering the integers (and then Gaussian integers)

Say that a polynomial recurrence relation (my terminology) for $f_i$ is: $k$ initial conditions setting $f_1,\ldots,f_k$ to integers ($\in \mathbb{Z})$. A recurrence equation of the form $f_i =$ a ...
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### Number of orbits of $\mathrm{SL}_2(\mathcal O_A)$ on $\mathbf P^1(A)$ when $A$ is a quaternion algebra

This is a reference request. Let $A$ be an anisotropic quaternion algebra over $\mathbf Q$. Let $\mathcal O_A$ be a maximal order in $A$. Then $\mathrm{SL}_2(A)$ acts transitively on the right on ...
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### What is the state of art MIQP solver

I used Gurobi with a MIQP with 26 binary variables and 26*4 interaction term without any other constraint. The speed is very slow already.... I want to ask what is the state of art of MIQP solvers. ...
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### Intersection points of closed curves inscribed in a convex polygon

Suppose that I have two distinct simple closed curves, $C_1$ & $C_2$, and each is inscribed in a convex polygon, D. By inscribed, I mean tangent to each side of D. In particular, I am most ...
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### Arranging books into bags [on hold]

I'm trying to find an algorithm to answer the following question (informal): given a (finite) set of distinct books of different (positive integer) sizes and a (finite) set of bags of different ...
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### In Dedekind' construction of real numbers, what's wrong with this understanding [on hold]

in this prove, every cut corresponds to a real number. and a cut is a subset of Q.and cut have these three properties.1.is not empty 2.if p belong to this cut,any qp so in my understanding, every cut ...