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We study geometric characterizations of unbounded integer polynomial optimization problems. While unboundedness along a ray fully characterizes unbounded integer linear and quadratic optimization problems, we show that this is not the case…

Optimization and Control · Mathematics 2025-11-06 Alberto Del Pia

We show that every quasi-compact and quasi-separated algebraic stack can be approximated by a noetherian algebraic stack. We give several applications such as eliminating noetherian hypotheses in the theory of good moduli spaces.

Algebraic Geometry · Mathematics 2023-11-16 David Rydh

In this note, we use integral binary cubic forms to study the rational cube sum problem. We prove (unconditionally) that for any positive integer $d$, infinitely many primes in each of the residue classes $ 1 \pmod {9d}$ as well as $ -1…

Number Theory · Mathematics 2024-06-03 Somnath Jha , Dipramit Majumdar , B. Sury

In 1974, M. B. Nathanson proved that every irrational number $\alpha$ represented by a simple continued fraction with infinitely many elements greater than or equal to $k$ is approximable by an infinite number of rational numbers $p/q$…

Number Theory · Mathematics 2024-07-17 Jaroslav Hančl , Tho Phuoc Nguyen

The theory of Gromov-Hausdorff convergence is applied to sequences of quotient rings of integers. It is shown the existence of limit rings (fields) as the Gromov-Hausdorff limits of sequences of metric quotient rings. The relation of these…

Rings and Algebras · Mathematics 2023-01-05 Ricardo Gallego Torromé

We prove that any open subset $U$ of a semi-simple simply connected quasi-split linear algebraic group $G$ with ${codim} (G\setminus U, G)\geq 2$ over a number field satisfies strong approximation by establishing a fibration of $G$ over a…

Algebraic Geometry · Mathematics 2018-05-22 Yang Cao , Yongqi Liang , Fei Xu

In a recent preprint by Deutsch et al. [1995] the authors suggest the possibility of polynomial approximability of arbitrary unitary operations on $n$ qubits by 2-qubit unitary operations. We address that comment by proving strong lower…

Quantum Physics · Physics 2008-02-03 E. Knill

We describe all special curves in the parameter space of complex cubic polynomials, that is all algebraic irreducible curves containing infinitely many post-critically finite polynomials. This solves in a strong form a conjecture by Baker…

Dynamical Systems · Mathematics 2016-06-21 Charles Favre , Thomas Gauthier

We establish the first effective improvements on the Liouville inequality for approximation to complex non-real algebraic numbers by complex algebraic numbers of degree at most 4.

Number Theory · Mathematics 2024-11-18 Prajeet Bajpai , Yann Bugeaud

We construct a countable family of multi-dimensional continued fraction algorithms, built out of five specific multidimensional continued fractions, and find a wide class of cubic irrational real numbers a so that either (a, a^2) or (a,…

Approximation in this paper is of vectors on the unit $d$-cube by the projection of integer lattice points onto the same cube. We define badly approximable vectors on a rational quadratic variety and show that sets of these vectors, which…

Number Theory · Mathematics 2011-10-31 Jimmy Tseng

We classify and enumerate all rational numbers with approximation constant at least $\frac{1}{3}$ using hyperbolic geometry. Rational numbers correspond to geodesics in the modular torus with both ends in the cusp, and the approximation…

Number Theory · Mathematics 2024-05-29 Boris Springborn

In this paper we establish properties of independence for the continued fraction expansions of two algebraic numbers. Roughly speaking, if the continued fraction expansions of two irrational algebraic numbers have the same long sub-word,…

Number Theory · Mathematics 2017-02-10 Xianzu Lin

We prove that Z in definable in Q by a formula with 2 universal quantifiers followed by 7 existential quantifiers. It follows that there is no algorithm for deciding, given an algebraic family of Q-morphisms, whether there exists one that…

Number Theory · Mathematics 2017-04-03 Bjorn Poonen

We investigate the large values of class numbers of cubic fields, showing that one can find arbitrary long sequences of "close" abelian cubic number fields with class numbers as large as possible. We also give a first step toward an…

Number Theory · Mathematics 2024-08-05 Jérémy Dousselin

In this paper, the Hermite problem has been approached finding a periodic representation (by means of periodic rational or integer sequences) for any cubic irrationality. In other words, the problem of writing cubic irrationals as a…

Number Theory · Mathematics 2014-01-17 Nadir Murru

We show that if $K$ is a monogenic, primitive, totally real number field, that contains units of every signature, then there exists a lower bound for the rank of integer universal quadratic forms defined over $K$. In particular, we extend…

Number Theory · Mathematics 2018-08-07 Pavlo Yatsyna

Let n be an odd number and F an imaginary quadratic field with odd discriminant. We show that there exists infinitely many cubic fields K such that the class number of K is divisible by n and the Galois closure of K contains F.

Number Theory · Mathematics 2007-05-23 Ivan Chipchakov , Kalin Kostadinov

We study how well a real number can be approximated by sums of two or more rational numbers with denominators up to a certain size.

Number Theory · Mathematics 2007-05-23 Tsz Ho Chan , Angel V. Kumchev

In this paper we discuss some properties of completely irrational subspaces. We prove that there exist completely irrational subspaces that are badly approximable and, moreover, sets of such subspaces are winning in different senses. We get…

Number Theory · Mathematics 2025-02-18 Vasiliy Neckrasov