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It is conjectured that all decomposable (i.e. interior can be triangulated without adding new vertices) polyhedra with vertices in convex position are infinitesimally rigid and only recently has it been shown that this is indeed true under…

Differential Geometry · Mathematics 2024-04-29 Jilly Kevo

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

In this work, we show the geometric properties of a family of polyhedra obtained by folding a regular tetrahedron along regular triangular grids. Each polyhedron is identified by a pair of nonnegative integers. The polyhedron can be cut…

Computational Geometry · Computer Science 2019-12-04 Seri Nishimoto , Takashi Horiyama , Tomohiro Tachi

We study the flexibility of suspensions (polyhedra having the combinatorial structure of dipyramids) that have an even number of vertexes and provide arguments that there are least five distinct types of flexible suspensions.

Metric Geometry · Mathematics 2014-04-10 Gerald D. Nelson

We study a class of mechanisms known as Kokotsakis polyhedra with a quadrangular base. These are $3\times3$ quadrilateral meshes whose faces are rigid bodies and joined by hinges at the common edges. In contrast to existing work, the…

Algebraic Geometry · Mathematics 2026-03-09 Yang Liu

Finding necessary conditions for the geometry of flexible polyhedra is a classical problem that has received attention also in recent times. For flexible polyhedra with triangular faces, we showed in a previous work the existence of cycles…

Metric Geometry · Mathematics 2022-05-24 Matteo Gallet , Georg Grasegger , Jan Legerský , Josef Schicho

We present structures comprised of identical convex polyhedra which are interlocked geometrically. These sets cannot be disassembled by removing individual polyhedra by translations and/or rotations. The shapes that permit interlocking…

Metric Geometry · Mathematics 2017-12-05 A. J. Kanel-Belov , A. V. Dyskin , Y. Estrin , E. Pasternak , I. A. Ivanov-Pogodaev

A polyhedron is flexible if it can be continuously deformed preserving the shape and dimensions of every its face. In the late 1970's Klaus Steffen constructed a sphere-homeomorphic embedded flexible polyhedron with triangular faces and…

Metric Geometry · Mathematics 2025-09-23 Victor Alexandrov , Evgenii Volokitin

An edge-unfolding of a polyhedron is produced by cutting along edges and flattening the faces to a *net*, a connected planar piece with no overlaps. A *grid unfolding* allows additional cuts along grid edges induced by coordinate planes…

Computational Geometry · Computer Science 2007-05-23 Mirela Damian , Robin Flatland , Joseph O'Rourke

Cyclohedra are a well-known infinite familiy of finite-dimensional polytopes that can be constructed from centrally symmetric triangulations of even-sided polygons. In this article we introduce an infinite-dimensional analogue and prove…

Group Theory · Mathematics 2014-11-14 Ariadna Fossas Tenas , Jon McCammond

Steffen's polyhedron was believed to have the least number of vertices among polyhedra that can flex without self-intersections. Maksimov clarified that the pentagonal bipyramid with one face subdivided into three is the only polyhedron…

Metric Geometry · Mathematics 2024-10-18 Matteo Gallet , Georg Grasegger , Jan Legerský , Josef Schicho

A new parametric surface representation is proposed that interpolates the vertices of a given closed mesh of arbitrary topology. Smoothly connecting quadrilateral patches are created by blending local, multi-sided quadratic interpolants. In…

Computational Geometry · Computer Science 2026-01-28 Péter Salvi

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

Poincar\'e's Polyhedron Theorem is a widely known valuable tool in constructing manifolds endowed with a prescribed geometric structure. It is one of the few criteria providing discreteness of groups of isometries. This work contains a…

Geometric Topology · Mathematics 2011-08-01 Sasha Anan'in , Carlos H. Grossi

We construct examples of embedded flexible cross-polytopes in the spheres of all dimensions. These examples are interesting from two points of view. First, in dimensions 4 and higher, they are the first examples of embedded flexible…

Metric Geometry · Mathematics 2024-11-20 Alexander A. Gaifullin

An unfolding of a polyhedron along its edges is called a vertex unfolding if adjacent faces are allowed to be connected at not only an edge but also a vertex. Demaine et al showed that every triangulated polyhedron has a vertex unfolding.…

Combinatorics · Mathematics 2013-02-19 Toshiki Endo , Yuki Suzuki

We construct compact polyhedra with $m$-gonal faces whose links are generalized 3-gons. It gives examples of cocompact hyperbolic bildings of type $P(m,3)$. For $m=3$ we get compact spaces covered by Euclidean buildings of type $A_2$.

Combinatorics · Mathematics 2007-05-23 Alina Vdovina

We discuss some recent results on flexible polyhedra and the bellows conjecture, which claims that the volume of any flexible polyhedron is constant during the flexion. Also, we survey main methods and several open problems in this area.

Metric Geometry · Mathematics 2016-05-31 Alexander A. Gaifullin

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 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