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We define a notion of a rotund quasi-uniform space and describe a new direct construction of a (right-continuous) quasi-pseudometric on a (rotund) quasi-uniform space. This new construction allows to give alternative proofs of several…

General Topology · Mathematics 2016-02-19 Taras Banakh , Alex Ravsky

A self-dual algebras is one isomorphic as a module to the opposite of its dual; a quasi self-dual algebra is one whose cohomology with coefficients in itself is isomorphic to that with coefficients in the opposite of its dual. For these…

K-Theory and Homology · Mathematics 2011-11-03 Murray Gerstenhaber

We consider quasiconformal deformations of $\mathbb{C}\setminus\mathbb{Z}$. We give some criteria for infinitely often punctured planes to be quasiconformally equivalent to $\mathbb{C}\setminus\mathbb{Z}$. In particular, we characterize the…

Differential Geometry · Mathematics 2014-12-30 Hiroki Fujino

We define the concept of an ultrametric M\"obius space and use this to characterize nonelementary geodesically complete trees.

Metric Geometry · Mathematics 2015-08-14 Jonas Beyrer , Viktor Schroeder

An order-theoretic forest is a countable partial order such that the set of elements larger than any element is linearly ordered. It is an order-theoretic tree if any two elements have an upper-bound. The order type of a branch can be any…

Logic in Computer Science · Computer Science 2023-06-22 Bruno Courcelle

Quasiconformal maps in the complex plane are homeomorphisms that satisfy certain geometric distortion inequalities; infinitesimally, they map circles to ellipses with bounded eccentricity. The local distortion properties of these maps give…

Complex Variables · Mathematics 2024-09-12 Rosemarie Bongers

It is proved the following theorem, if $w$ is a quasiconformal harmonic mappings between two Riemann surfaces with smooth boundary and aproximate analytic metric, then $w$ is a quasi-isometry with respect to Euclidean metric.

Complex Variables · Mathematics 2011-08-03 David Kalaj

We prove that if $f:\mathbb{B}^n \to \mathbb{B}^n$, for $n\geq 2$, is a homeomorphism with bounded skew over all equilateral hyperbolic triangles, then $f$ is in fact quasiconformal. Conversely, we show that if $f:\mathbb{B}^n \to…

Complex Variables · Mathematics 2019-09-26 C. Ackermann , A. Fletcher

We investigate the connections between tree amalgamations and quasi-isometries. In particular, we prove that the quasi-isometry type of multi-ended accessible quasi-transitive connected locally finite graphs is determined by the…

Combinatorics · Mathematics 2018-12-13 Matthias Hamann

In every dimension $n\ge 3$ we introduce a class of orthogonal graph-manifolds and prove that the fundamental group of any orthogonal graph-manifold quasi-isometrically embeds into a product of $n$ trees. As a consequence, we obtain that…

Geometric Topology · Mathematics 2012-04-27 Alexander Smirnov

We introduce the quasi-ordinarization transform of a numerical semigroup. This transform will allow to organize all the semigroups of a given genus in a forest rooted at all quasi-ordinary semigroups with the given genus. This construction…

Combinatorics · Mathematics 2021-06-16 Maria Bras-Amorós , Hebert Pérez-Rosés , José Miguel Serradilla-Merinero

We give a combinatorial characterization of the group of quasiconformal homeomorphisms of a closed, oriented surface $S$ of genus at least $2$. In particular, we prove they are exactly the automorphisms of a graph of essential quasicircles…

Geometric Topology · Mathematics 2026-01-16 Katherine Williams Booth , Alexander Nolte , Yvon Verberne

We show that any compact, connected set $K$ in the plane can be approximated by the critical points of a polynomial with two critical values. Equivalently, $K$ can be approximated in the Hausdorff metric by a true tree in the sense of…

Complex Variables · Mathematics 2020-07-09 Christopher J. Bishop

We present a streamlined exposition of a construction by R. Chen, A. Poulin, R. Tao, and A. Tserunyan, which proves the treeability of equivalence relations generated by any locally-finite Borel graph such that each component is a…

Logic · Mathematics 2025-04-25 Zhaoshen Zhai

We establish an upper estimate for the coefficient of quasiconformal reflection with respect to the boundary of an arbitrary isosceles trapezoid in terms of its geometric parameters; the estimate improve the result obtained in the recent…

Complex Variables · Mathematics 2024-08-06 A. Kushaeva , K. Kushaeva , S. Nasyrov

Using uniformization, Cantor type sets can be regarded as boundaries of rooted trees. In this setting, we show that the trace of a first-order Sobolev space on the boundary of a regular rooted tree is exactly a Besov space with an explicit…

Functional Analysis · Mathematics 2017-05-08 Anders Björn , Jana Björn , James T. Gill , Nageswari Shanmugalingam

We characterise when there exists a quasiisometric embedding between two solvable Baumslag-Solitar groups. This extends the work of Farb and Mosher on quasiisometries between the same groups. More generally, we characterise when there can…

Group Theory · Mathematics 2022-04-11 Patrick S. Nairne

In this paper, we study metric trees, without any finiteness restrictions. For subsets of such trees, a condition that guarantees that the Hausdorff and Gromov--Hausdorff distances from the subset to the entire metric tree are the same is…

Metric Geometry · Mathematics 2024-12-30 A. O. Ivanov , I. N. Mikhailov , A. A. Tuzhilin

This paper demonstrates that every ultrametric space is homeomorphic to a clade space of a pruned tree, i.e., a subspace of a tree's canopy. Furthermore, it characterizes several topological properties of ultrametrizable spaces through the…

General Topology · Mathematics 2024-08-01 Itamar Bellaïche

Weak similarities form a special class of mappings between semimetric spaces. Two semimetric spaces $X$ and $Y$ are weakly similar if there exists a weak similarity $\Phi\colon X\to Y$. We find a structural characteristic of finite…

General Topology · Mathematics 2024-12-31 Evgeniy Petrov