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The associahedron is a convex polytope whose face poset is based on nonintersecting diagonals of a convex polygon. In this paper, given an arbitrary simple polygon P, we construct a polytopal complex analogous to the associahedron based on…

Combinatorics · Mathematics 2015-06-16 Satyan L. Devadoss , Rahul Shah , Xuancheng Shao , Ezra Winston

In this note, we obtain a new result concluding when contact (+1/n)-surgery is overtwisted. We give a counterexample to a conjecture by James Conway on overtwistedness of manifolds obtained by contact surgery. We list some problems related…

Geometric Topology · Mathematics 2017-10-09 Sinem Onaran

In this paper, we consider the problem of representing graphs by polygons whose sides touch. We show that at least six sides per polygon are necessary by constructing a class of planar graphs that cannot be represented by pentagons. We also…

Computational Geometry · Computer Science 2015-03-19 Christian A. Duncan , Emden R. Gansner , Yifan Hu , Michael Kaufmann , Stephen G. Kobourov

How can a stack of identical blocks be arranged to extend beyond the edge of a table as far as possible? We consider a generalization of this classic puzzle to blocks that differ in width and mass. Despite the seemingly simple premise, we…

Combinatorics · Mathematics 2026-02-13 Simon Gmeiner , Andreas S. Schulz

It is well known that a graph is bipartite if and only if the spectrum of its adjacency matrix is symmetric. In the present paper, this assertion is dissected into three separate matrix results of wider scope, which are extended also to…

Combinatorics · Mathematics 2016-05-11 V. Nikiforov

The purpose of this article is to investigate the relationship between suborbifolds and orbifold embeddings. In particular, we give natural definitions of the notion of suborbifold and orbifold embedding and provide many examples.…

Differential Geometry · Mathematics 2015-11-25 Joseph E. Borzellino , Victor Brunsden

A general (convex) polytope $P\subset\mathbb R^d$ and its edge-graph $G_P$ can have very distinct symmetry properties. We construct a coloring (of the vertices and edges) of the edge-graph so that the combinatorial symmetry group of the…

Metric Geometry · Mathematics 2021-11-08 Martin Winter

It is conjectured that every manifold admitting an Anosov diffeomorphism is, up to homeomorphism, finitely covered by a nilmanifold. Motivated by this conjecture, an important problem is to determine which nilmanifolds admit an Anosov…

Dynamical Systems · Mathematics 2015-01-13 Jonas Deré

Piecewise Euclidean structures (identified solid Euclidean polyhedra) on topological 3-dimensional manifolds and pseudo-manifolds are constructed so that they admit pseudo-foliations, a generalized type of foliation. The construction of…

Differential Geometry · Mathematics 2007-05-23 Simon P Morgan

Modeling folding surfaces with nonzero thickness is of practical interest for mechanical engineering. There are many existing approaches that account for material thickness in folding applications. We propose a new systematic and broadly…

Computational Geometry · Computer Science 2016-01-22 Jason S. Ku , Erik D. Demaine

Non-Hermitian systems exhibit interesting band structures, where novel topological phenomena arise from the existence of exceptional points at which eigenvalues and eigenvectors coalesce. One important open question is how this would…

Mesoscale and Nanoscale Physics · Physics 2023-10-20 Marcus Stålhammar , Cristiane Morais Smith

Band structure unfolding is a key technique for analyzing and simplifying the electronic band structure of large, internally distorted supercells that break the primitive cell's translational symmetry. In this work, we present an efficient…

Materials Science · Physics 2026-02-10 Jingkai Quan , Nikita Rybin , Matthias Scheffler , Christian Carbogno

We study symmetries between untwisted and twisted strings on asymmetric orbifolds. We present a list of asymmetric orbifold models to possess intertwining currents which convert untwisted string states to twisted ones, and vice versa. We…

High Energy Physics - Theory · Physics 2009-10-22 Y. Imamura , M. Sakamoto , T. Sasada , M. Tabuse

The conventional topological description given by the fundamental group of nematic order parameter does not adequately explain the entangled defect line structures that have been observed in nematic colloids. We introduce a new topological…

Soft Condensed Matter · Physics 2011-05-09 Simon Čopar , Slobodan Žumer

We describe four hyperbolic knot complements in $\mathbb{S}^3$, each of which covers a prism orbifold: the quotient of $\mathbb{H}^3$ by the action of a discrete group generated by reflections in the faces of a polyhedron that has the…

Geometric Topology · Mathematics 2026-03-27 Jason DeBlois , Arshia Gharagozlou , Neil R Hoffman

The anomaly of non-invertible higher-form symmetries is determined by the braiding of topological operators implementing them. In this paper, we study a method to classify braidings on topological line and surface operators by leveraging…

High Energy Physics - Theory · Physics 2025-03-19 Pavel Putrov , Rajath Radhakrishnan

We show that several classes of polyhedra are joined by a sequence of O(1) refolding steps, where each refolding step unfolds the current polyhedron (allowing cuts anywhere on the surface and allowing overlap) and folds that unfolding into…

Computational Geometry · Computer Science 2023-10-27 Erik D. Demaine , Martin L. Demaine , Jenny Diomidova , Tonan Kamata , Ryuhei Uehara , Hanyu Alice Zhang

We automatically verify the crucial steps in the original proof of correctness of an algorithm which, given a geometric graph satisfying certain additional properties removes edges in a systematic way for producing a connected graph in…

Logic in Computer Science · Computer Science 2023-11-30 Lucas Böltz , Viorica Sofronie-Stokkermans , Hannes Frey

A promising strategy for better understanding space and time at the Planck scale, is outlined and further pursued. It is explained in detail, how black hole unitarity demands the existence of transformations that can remove firewalls. This…

General Relativity and Quantum Cosmology · Physics 2017-09-12 Gerard t Hooft

We extend the notion of star unfolding to be based on a quasigeodesic loop Q rather than on a point. This gives a new general method to unfold the surface of any convex polyhedron P to a simple (non-overlapping), planar polygon: cut along…

Computational Geometry · Computer Science 2009-06-24 Jin-ichi Itoh , Joseph O'Rourke , Costin Vîlcu