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Let X be an irreducible variety and Bir(X) its group of birational transformations. We show that the group structure of Bir(X) determines whether X is rational and whether X is ruled. Additionally, we prove that any Borel subgroup of Bir(X)…

Algebraic Geometry · Mathematics 2024-09-13 Andriy Regeta , Christian Urech , Immanuel van Santen

Let $k$ be an infinite field. The notion of retract $k$-rationality was introduced by Saltman in the study of Noether's problem and other rationality problems. We will investigate the retract rationality of a field in this paper. Theorem 1.…

Algebraic Geometry · Mathematics 2011-10-07 Ming-chang Kang

We present a new asynchronous model of computation named Stellar Resolution based on first-order unification. This model of computation is obtained as a formalisation of Girard's transcendental syntax programme, sketched in a series of…

Logic in Computer Science · Computer Science 2020-08-03 Boris Eng , Thomas Seiller

The underperformance of existing multimodal large language models for time series reasoning lies in the absence of rationale priors that connect temporal observations to their downstream outcomes, which leads models to rely on superficial…

Artificial Intelligence · Computer Science 2026-01-07 Qingxiang Liu , Zhiqing Cui , Xiaoliang Luo , Yuqian Wu , Zhuoyang Jiang , Huaiyu Wan , Sheng Sun , Lvchun Wang , Wei Yu , Yuxuan Liang

We introduce and study some families of groups whose irreducible characters take values on quadratic extensions of the rationals. We focus mostly on a generalization of inverse semi-rational groups, which we call uniformly semi-rational…

Group Theory · Mathematics 2025-07-01 Ángel del Río , Marco Vergani

We study an extension of $\mtl$ in pointwise time with rational expression guarded modality $\reg_I(\re)$ where $\re$ is a rational expression over subformulae. We study the decidability and expressiveness of this extension ($\mtl$+$\varphi…

Logic in Computer Science · Computer Science 2017-05-04 Shankara Narayanan Krishna , Khushraj Madnani , P. K. Pandya

This article is interested in pullbacks under the logarithmic derivative of algebraic ordinary differential equations. In particular, assuming the solution set of an equation is internal to the constants, we would like to determine when its…

Logic · Mathematics 2025-03-20 Christine Eagles , Léo Jimenez

We consider an extension of linear-time temporal logic (LTL) with both local and remote data constraints interpreted over a concrete domain. This extension is a natural extension of constraint LTL and the Temporal Logic of Repeating Values,…

Logic in Computer Science · Computer Science 2022-06-06 Ashwin Bhaskar

If $V$ is a smooth projective variety defined over a local field $K$ with finite residue field, so that its \'etale cohomology over the algebraic closure $\bar{K}$ is supported in codimension 1, then the mod $p$ reduction of a projective…

Number Theory · Mathematics 2007-05-23 Hélène Esnault

We study the structure of the rational motivic stable homotopy category over general base schemes. Our first class of results concerns the six operations: we prove absolute purity, stability of constructible objects, and…

Algebraic Geometry · Mathematics 2021-03-15 Frédéric Déglise , Jean Fasel , Adeel A. Khan , Fangzhou Jin

A theorem of alternatives provides a reduction of validity in a substructural logic to validity in its multiplicative fragment. Notable examples include a theorem of Arnon Avron that reduces the validity of a disjunction of multiplicative…

Logic · Mathematics 2020-02-27 Almudena Colacito , Nikolaos Galatos , George Metcalfe

We study a particular plane curve over a finite field whose normalization is of genus 0. The number of rational points of this curve achieves the Aubry-Perret bound for rational curves. The configuration of its rational points and a…

Algebraic Geometry · Mathematics 2011-08-23 Satoru Fukasawa , Masaaki Homma , Seon Jeong Kim

A generalization of Hurwitz stable polynomials to real rational functions is considered. We establishe an analogue of the Hurwitz stability criterion for rational functions and introduce a new type of determinants that can be treated as a…

Classical Analysis and ODEs · Mathematics 2025-07-01 Yury S. Barkovsky , Mikhail Tyaglov

This work studies existence and regularity questions for attracting invariant tori in three dimensional dissipative systems of ordinary differential equations. Our main result is a constructive method of computer assisted proof which…

Dynamical Systems · Mathematics 2020-01-14 Maciej J. Capinski , Emmanuel Fleurantin , Jason D. Mireles James

Strict-Tolerant Logic (ST) underpins naive theories of truth and vagueness (respectively including a fully disquotational truth predicate and an unrestricted tolerance principle) without jettisoning any classically valid laws. The classical…

Logic · Mathematics 2026-03-02 Francesco Paoli , Adam Přenosil

We extend the validity of the Penrose singularity theorem to spacetime metrics of regularity $C^{1,1}$. The proof is based on regularisation techniques, combined with recent results in low regularity causality theory.

General Relativity and Quantum Cosmology · Physics 2016-09-15 Michael Kunzinger , Roland Steinbauer , James A. Vickers

The conjecture due to Bertrand and Rodriguez Villegas asserts that the 1-norm of the nonzero element in an exterior power of the units of a number field has a certain lower bound. We prove this conjecture for the exterior square case when…

Number Theory · Mathematics 2024-10-07 Dohyeong Kim , Seungho Song

We study Tao's finitary viewpoint of convergence in metric spaces, as captured by the notion of metastability. We adopt the perspective of continuous model theory. We show that, in essence, metastable convergence with a given rate is the…

Functional Analysis · Mathematics 2019-02-26 Eduardo Dueñez , José N. Iovino

This paper examines how a notion of stable explanation developed elsewhere in Defeasible Logic can be expressed in the context of formal argumentation. With this done, we discuss the deontic meaning of this reconstruction and show how to…

Artificial Intelligence · Computer Science 2023-07-12 Cecilia Di Florio , Guido Governatori , Antonino Rotolo , Giovanni Sartor

<p>We address the general problem of determining the validity of boolean combinations of equalities and inequalities between real-valued expressions. In particular, we consider methods of establishing such assertions using only restricted…

Logic in Computer Science · Computer Science 2017-01-11 Jeremy Avigad , Harvey Friedman