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A branched covering $f: S^2 \to S^2$ is a nearly Euclidean Thurston (NET) map if each critical point is simple and its postcritical set has exactly four points. We show that up to equivalence, each NET map admits a normal form in terms of…

Dynamical Systems · Mathematics 2017-01-03 William Floyd , Walter Parry , Kevin M. Pilgrim

We demonstrate that the question whether or not a given postcritically finite topological ramified covering map of the 2-sphere is Thurston equivalent to a rational map is algorithmically decidable.

Dynamical Systems · Mathematics 2010-09-30 Sylvain Bonnot , Mark Braverman , Michael Yampolsky

A Thurston map is called nearly Euclidean if its local degree at each critical point is 2 and it has exactly four postcritical points. Nearly Euclidean Thurston (NET) maps are simple generalizations of rational Lattes maps. We investigate…

Dynamical Systems · Mathematics 2015-07-07 Edgar A. Saenz

We investigate the combinatorial and dynamical properties of so-called nearly Euclidean Thurston maps, or NET maps. These maps are perturbations of many-to-one folding maps of an affine two-sphere to itself. The close relationship between…

Dynamical Systems · Mathematics 2017-08-24 William Floyd , Gregory Kelsey , Sarah Koch , Russell Lodge , Walter Parry , Kevin M. Pilgrim , Edgar Saenz

We focus on rational solutions or nearly-feasible rational solutions that serve as certificates of feasibility for polynomial optimization problems. We show that, under some separability conditions, certain cubic polynomially constrained…

Optimization and Control · Mathematics 2022-04-15 Daniel Bienstock , Alberto del Pia , Robert Hildebrand

We introduce and study a class of Thurston maps from the 2-sphere to itself which we call nearly Euclidean Thurston (NET) maps. These are simple generalizations of Euclidean Thurston maps.

Dynamical Systems · Mathematics 2012-04-17 James W. Cannon , William J. Floyd , Walter R. Parry , Kevin M. Pilgrim

The dynamical classification of rational maps is a central concern of holomorphic dynamics. Much progress has been made, especially on the classification of polynomials and some approachable one-parameter families of rational maps; the goal…

Dynamical Systems · Mathematics 2022-01-10 Russell Lodge , Yauhen Mikulich , Dierk Schleicher

This paper studies whether rationality can be computed. Rationality is defined as the use of complete information, which is processed with a perfect biological or physical brain, in an optimized fashion. To compute rationality one needs to…

Artificial Intelligence · Computer Science 2018-12-27 Tshilidzi Marwala

Let $\varphi:\mathbb{P}^1(\mathbb F_q)\to\mathbb{P}^1(\mathbb F_q)$ be a rational map of degree $d>1$ on a fixed finite field. We give asymptotic formulas for the size of image sets $\varphi^n(\mathbb{P}^1(\mathbb F_q))$ as a function of…

Number Theory · Mathematics 2019-11-07 Jamie Juul

Rational and neural network based approximations are efficient tools in modern approximation. These approaches are able to produce accurate approximations to nonsmooth and non-Lipschitz functions, including multivariate domain functions. In…

Optimization and Control · Mathematics 2023-09-08 Vinesha Peiris , Reinier Diaz Millan , Nadezda Sukhorukova , Julien Ugon

We extend Thurston's combinatorial criterion for postcritically finite rational maps to a class of rational maps with bounded type Siegel disks. The combinatorial characterization of this class of Siegel rational maps plays a special role…

Dynamical Systems · Mathematics 2008-11-20 Gaofei Zhang

We study the expressivity of rational neural networks (RationalNets) through the lens of algebraic geometry. We consider rational functions that arise from a given RationalNet to be tuples of fractions of homogeneous polynomials of fixed…

Algebraic Geometry · Mathematics 2025-09-16 Alexandros Grosdos , Elina Robeva , Maksym Zubkov

We analyse the axioms of Euclidean geometry according to standard object-oriented software development methodology. We find a perfect match: the main undefined concepts of the axioms translate to object classes. The result is a suite of C++…

Computational Geometry · Computer Science 2009-09-29 M. H. van Emden , B. Moa

We consider postcritically finite rational maps $f\colon \widehat{\mathbb{C}} \to \widehat{\mathbb{C}}$ whose Julia set is the whole Riemann sphere $\widehat{\mathbb{C}}$. We call such a map an expanding rational Thurston map. Identifying…

Complex Variables · Mathematics 2025-10-22 Daniel Meyer , Julia Münch

A study of real quadratic maps with real critical points, emphasizing the effective construction of critically finite maps with specified combinatorics. We discuss the behavior of the Thurston algorithm in obstructed cases, and in one…

Dynamical Systems · Mathematics 2021-11-08 Araceli Bonifant , John Milnor , Scott Sutherland

We provide new examples of integrable rational maps in four dimensions with two rational invariants, which have unexpected geometric properties, as for example orbits confined to non algebraic varieties, and fall outside classes studied by…

Exactly Solvable and Integrable Systems · Physics 2018-11-06 N. Joshi , CM. Viallet

Let $X,Y$ be two irreducible subvarieties of the projective space $\mathbb{P}^n$, and $d\geq 1$ an integer number. The main result of this paper is an algorithm to construct {\bf explicitly}, in terms of $d$ and the ideals defining $X$ and…

Algebraic Geometry · Mathematics 2018-07-13 Tuyen Trung Truong

In this manuscript, we show that any neural network with any activation function can be represented as a decision tree. The representation is equivalence and not an approximation, thus keeping the accuracy of the neural network exactly as…

Machine Learning · Computer Science 2022-10-26 Caglar Aytekin

In the early 1980's Thurston gave a topological characterization of rational maps whose critical points have finite iterated orbits (\cite{Th,DH1}): given a topological branched covering $F$ of the two sphere with finite critical orbits, if…

Dynamical Systems · Mathematics 2014-07-15 Cui Guizhen , Tan Lei

We investigate rational maps with period one and two cluster cycles. Given the definition of a cluster, we show that, in the case where the degree is $d$ and the cluster is fixed, the Thurston class of a rational map is fixed by the…

Dynamical Systems · Mathematics 2011-08-25 Thomas Sharland
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