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We show that no minimal vertex triangulation of a closed, connected, orientable 2-manifold of genus 6 admits a polyhedral embedding in R^3. We also provide examples of minimal vertex triangulations of closed, connected, orientable…

Metric Geometry · Mathematics 2008-01-18 Lars Schewe

We prove that every three-dimensional polyhedron is uniquely determined by its dihedral angles and edge lengths, even if nonconvex or self-intersecting, under two plausible sufficient conditions: (i) the polyhedron has only convex faces and…

Geometric Topology · Mathematics 2023-07-28 Yunhi Cho , Seonhwa Kim

Skeletal polyhedra and polygonal complexes in ordinary Euclidean 3-space are finite or infinite 3-periodic structures with interesting geometric, combinatorial, and algebraic properties. They can be viewed as finite or infinite 3-periodic…

Metric Geometry · Mathematics 2014-03-04 Egon Schulte

Given n >= 4 positive real numbers, we prove in this note that they are the face areas of a convex polyhedron if and only if the largest number is not more than the sum of the others.

Discrete Mathematics · Computer Science 2011-01-06 Joseph O'Rourke

We construct a sequence of convex polyhedra on n vertices with the property that, as n -> infinity, the fraction of its edge unfoldings that avoid overlap approaches 0, and so the fraction that overlap approaches 1. Nevertheless, each does…

Computational Geometry · Computer Science 2008-01-28 Alex Benton , Joseph O'Rourke

We give a complete description of all convex polyhedra whose surface can be constructed from several congruent regular pentagons by folding and gluing them edge to edge. Our method of determining the graph structure of the polyhedra from a…

Computational Geometry · Computer Science 2020-07-06 Elena Arseneva , Stefan Langerman , Boris Zolotov

We define a new class of orthogonal polyhedra, called orthogrids, that can be unfolded without overlap with constant refinement of the gridded surface.

Computational Geometry · Computer Science 2013-10-18 Mirela Damian , Erik Demaine , Robin Flatland

The shape of crystalline nanoparticles (NP) can often be described by polyhedra with flat facet surfaces. Thus, structural studies of polyhedral bodies can help to describe geometric details of NPs. Here we consider compact polyhedra of…

Mesoscale and Nanoscale Physics · Physics 2023-07-24 Klaus E. Hermann

Polypolyhedra (after R. Lang) are compounds of edge-transitive 1-skeleta. There are 54 topologically different polypolyhedra, and each has icosidodecahedral, cuboctahedral, or tetrahedral symmetry, all are realizable as modular origami…

Metric Geometry · Mathematics 2016-01-14 Sarah-Marie Belcastro , Thomas C. Hull

This paper studies the straight skeleton of polyhedra in three dimensions. We first address voxel-based polyhedra (polycubes), formed as the union of a collection of cubical (axis-aligned) voxels. We analyze the ways in which the skeleton…

Computational Geometry · Computer Science 2008-05-02 Gill Barequet , David Eppstein , Michael T. Goodrich , Amir Vaxman

We show the existence of families of periodic polyhedra in spaces of constant curvature whose fundamental domains can be obtained by attaching prisms and antiprisms to Archimedean solids. These polyhedra have constant discrete curvature and…

Differential Geometry · Mathematics 2024-01-09 Christina Duffield , Daniel Freese , William Holt , Matthias Weber , Ramazan Yol

It is unknown whether every polycube (polyhedron constructed by gluing cubes face-to-face) has an edge unfolding, that is, cuts along edges of the cubes that unfolds the polycube to a single nonoverlapping polygon in the plane. Here we…

Computational Geometry · Computer Science 2022-05-24 Erik D. Demaine , Martin L. Demaine , David Eppstein , Joseph O'Rourke

A polygonal complex in euclidean 3-space is a discrete polyhedron-like structure with finite or infinite polygons as faces and finite graphs as vertex-figures, such that a fixed number r of faces surround each edge. It is said to be regular…

Metric Geometry · Mathematics 2009-06-08 Daniel Pellicer , Egon Schulte

Let a polygon be composed of equal rectangles. We find all quadratic irrationals r for which the polygon can be tiled by similar rectangles with given side ratio r.

Combinatorics · Mathematics 2021-11-29 Ivan Novikov

In this paper we have discussed different possible orthogonalities in matrices, namely orthogonal, quasi-orthogonal, semi-orthogonal and non-orthogonal matrices including completely positive matrices, while giving some of their…

Discrete Mathematics · Computer Science 2007-05-23 R. N. Mohan

We study polyiamonds (polygons arising from the triangular grid) that fold into the smallest yet unstudied platonic solid -- the octahedron. We show a number of results. Firstly, we characterize foldable polyiamonds containing a hole of…

Computational Geometry · Computer Science 2022-07-29 Eva Stehr , Linda Kleist

Using the orthogonal connectedness, we introduce the notion of orthogonal decomposability of convex polytopes and study it in the case of Platonic and Archimedean solids. While doing so, we also encounter polytopes which are not…

Combinatorics · Mathematics 2026-03-10 Julia Q. Du , Xuemei He , Xiaotian Song , Daniela Stiller , Liping Yuan , Tudor Zamfirescu

We study the Art Gallery Problem for face guards in polyhedral environments. The problem can be informally stated as: how many (not necessarily convex) windows should we place on the external walls of a dark building, in order to completely…

Computational Geometry · Computer Science 2014-04-22 Giovanni Viglietta

A Klein polyhedron is defined as the convex hull of nonzero lattice points inside an orthant of $\R^n$. It generalizes the concept of continued fraction. In this paper facets and edge stars of vertices of a Klein polyhedron are considered…

Number Theory · Mathematics 2007-05-23 Oleg N. German

In 1957, Steinhaus proved that a chain of regular tetrahedra, meeting face-to-face and forming a closed loop does not exist. Over the years, various modifications of this statement have been considered and analysed. Weakening the statement…

Combinatorics · Mathematics 2024-11-25 Reymond Akpanya , Vanishree Krishna Kirekod , Alice C. Niemeyer , Daniel Robertz