共 188 个问题,第 9/10 页
When are these quadratic forms surjective from $R^n$ to $R^n$?
Consider functions from $R^n$ to a subset of $R^n$. So $f(x_1,x_2,...,x_n) = (y_1,y_2,...,y_n)$. where $x_i,y_i$ are all real. More specific consider $$f(x_1,x_2,...,x_n) = (Q_1(x_1,x_2,...,x_n),Q_2(x_1,x_2,...,x_n),...,Q_n(x_1,x_2,...,x_n))$$ where the $Q_i$ are all Quadratic forms. Even more...
Is the Seive of Eratosthens a Breadth First Search Algorithm?
Numbers that are not yet mapped to are marked prime and given their own "trees", but really they are distance $\infty$ from the other primes. Traditionally, in a connected graph, BFS forms one tree, but really this is a collection of overlapping trees. What we have on the number line is a...
New primitives $3(a^3+b^3+c^3+a+b+c)+5(a^2+b^2+c^2)+2(a^2b+b^2c+ac^2)+4(a^2c+bc^2+ab^2+ab+bc+ac)=0$
$$3(a^3+b^3+c^3+a+b+c)+5(a^2+b^2+c^2)+2(a^2b+b^2c+ac^2)+4(a^2c+bc^2+ab^2+ab+bc+ac)=0$$ A table of primitives known to me $(a, b, c)$, $a \in{Z}$, $b\in \mathbb{Z}$, $c\in \mathbb{Z}^+$ $$ \boxed{\begin{array} {|r|r|r|r|}\hline №(a,b,c)& a_n & b_n & c_n \\ \hline S_1 & 0 & 0 & 0 \\ \hline S_2 & 0...
$\Pi$-orbits of elliptic curve covers
Let $$ \mathcal S=(\mathcal I,\Gamma,\Pi) $$ be a seam marked seed built from four compact oriented $2$-dimensional complex orbifold sheets. Each sheet is assumed to be a football type orbifold: its coarse underlying Riemann surface is $$ |\mathcal O_i|\cong \mathbb P^1 $$ and it has two...
$(20.108)$ in Iwaniec and Kowalski
Let $A\in GL(r,\mathbb{Z})$ be a positive definite matrix, $Q(x)=\dfrac{1}{2} x^t A x$ be the quadratic form associate to $A$, $Q^*(x)=\dfrac{1}{2} x^t A^{-1} x$ be the adjoint form of $Q(x)$ . Given $(c,d)=1,m\in\mathbb{Z}^r,$ we define $$G_m\left(\dfrac{d}{c}\right)=\sum_{h\,\text{mod}\,c}...
iterated forward difference operator applied to primes, OEIS A007442
I apply the iterated forward difference operator to the sequence of primes; from $$ (p_n) = (2, 3, 5, 7, 11 \ldots) $$ I get $$ (d^1_n) = (1, 2, 2, 4 \ldots) $$ $$ (d^2_n) = (1, 0, 2 \ldots) $$ $$ (d^3_n) = (-1, 2 \ldots) $$ $$ \ldots $$ For each sequence $(x_n)$, one can reconstruct the...
Stability of the leading Laurent term under a small perturbation for polynomial coordinates of $\mathbb A^2$
Suppose that $$ x=u^{-d},\qquad y=f(u), $$ where $$ d\in \mathbb Z_{>0},\qquad f(u)\in \mathbb C((u)), \qquad y=o(x). $$ Equivalently, $\operatorname{ord}_u f(u)>-d$. Let $ (P,Q)\in \operatorname{Aut}_{\mathbb C}\mathbb C[x,y]$ be a polynomial coordinate system, and write $$ X=P(x,y),\qquad...
Is there a research program that attempts to reconstruct an underlying structure from the statistical properties of the Riemann zeros?
I am a curious outsider to mathematics and recently started reading about the Riemann Hypothesis. I am aware that many outsiders mistakenly believe they have solved the Riemann Hypothesis. I am not making such a claim. I am only trying to understand whether this perspective already exists in the...
Minimum value of $i$ to change $\lfloor n / i \rfloor$
I was solving this CSES question called Sum of Divisors and one of the solutions in the USACO Guide hints at this statement: The minimum value of $j > i$ such that $\lfloor n/j \rfloor$ < $\lfloor n/i \rfloor$ is $j = \lfloor n/q \rfloor + 1$, where $q = \lfloor n/i \rfloor$ for integers $j, i...
Finding the equation of a tangent line to a projective curve at a non-singular point.
I am currently working through Fulton's Algebraic Curves and I have attempted the following problem: $$\text{Let P be a simple (non-singular) point on }F\text{ . Show that the tangent line to }F \text{ at } P\text{ has the equation }F_X (P )X + F_Y (P )Y + F_Z (P )Z = 0$$ My solution thus far...
An elliptic curve for $x_1^5+x_2^5+x_3^5=y_1^5+2y_2^5$?
In a prior post, the equation, $$x_1^5+2x_2^5 = y_1^5+2y_2^5$$ was considered. It has only one known primitive solution. This present post considers the similar, $$x_1^k+x_2^k+x_3^k = y_1^k+2y_2^k$$ valid for both $k = (1,5)$. Duncan Moore found only one primitive solution, namely, $$85333^k +...
Direct calculation of $H_1$ of the cotangent complex
Let $k$ be a commutative ring and let $A$ be a commutative $k$-algebra. The cotangent complex $\mathbf{L}_{A \mid k}$ can be computed using a simplicial resolution of $A$ as follows: choose a simplicial commutative $k$-algebra $P$ and an augmentation $\epsilon : P_0 \to A$ (i.e. a $k$-algebra...
What conditions are needed for intersection number of Cartier divisors to equal dimension of global sections?
Vakil, Definition 20.1.1: Let $X$ be a variety (reduced separated finite type scheme, actually I'm not sure if we need all this. I think we can get away with dropping "reduced" and "separated" and just assume $X$ is a finite type scheme) over a field $k$ (not necessarily algebraically closed)....
Number theory - why does the dot product on the Minkowski embedding resemble the Frobenius inner product?
The trace form $(a,b)\mapsto \mathrm{tr}(ab)$ is easily motivated as a choice of bilinear form on a number field $K$ by noting that it agrees with the (standard real) dot product on $\mathbb{R}^{r_1}×\mathbb{C}^{r_2}$ as restricted to the Minkowski embedding of $K$ (the one that sends a number...
Dyadic dissection with major arcs
In Vaughan's paper "A variance for k-free numbers in arithmetic progressions" https://londmathsoc.onlinelibrary.wiley.com/doi/abs/10.1112/S0024611505015352 he uses at one point a kind of dyadic decomposition for major arcs. From my understanding, I think he has $$\sum _{q\leq R}\int_{|\beta...
Computing Cartier Divisor from Weil Divisor Example
I am trying to work through the following problem: Let $k$ be a field, and let $X = \operatorname{Spec} k[x, y, z, w]/(xy−zw)\subseteq \mathbb{A}^4_ k.$ (a) Show that $D= V (x, z)$ is a prime (Weil) divisor on $X$ and that $\operatorname{Cl} X\simeq \mathbb{Z}$ is generated by the divisor class...
When is passing from real algebraic geometry to the complexification genuinely unavoidable?
Many results in real algebraic geometry are proved by passing from a real variety to its complexification , then studying the action of complex conjugation on . For example, one often regards $X(\mathbb R)$ as the fixed-point locus of conjugation on $X(\mathbb C)$. This appears in results such...
Non-openness of flat locus
If $f \colon X \to Y$ is a finite surjective morphism between integral Noetherian schemes, then the set $V\subseteq Y$ of points over which $f$ is flat is open. I want to show that this fails if we drop the finiteness assumption. I can think of an example given by blowing up $\mathbb A^3$ at a...
Title. Analytic validity of mapping the regularized sum of natural numbers to the sum of primes via a scalar product projection?
Title Analytic validity of mapping the regularized sum of natural numbers to the sum of primes via a scalar product projection Body In a recent preprint by Ezadiin Redwaan titled "A Scalar Product Approach to Strong Goldbach, Twin Primes, Polignac Conjectures And Geometric Unification of...
Question about Theorem 4.2 from Rational Points on Elliptic Curves
I have a question about a certain part of the proof of Theorem 4.2 from Rational Points on Elliptic Curves. Let $p$ be a prime so that $p=1\;\mathrm{mod}\;3$. Let $R=\{x^{3}|x\in\mathbb{F}_{p},x\neq 0\}$. Notation: $[XYZ]$ is the number of triples $(x,y,z)$ so that $x+y+z=0,x\in X,y\in Y,z\in...