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This note establishes that every polyhedron that has a Hamiltonian quasigeodesic can be edge-unfolded to a net, and shows that the class of such polyhedra is infinite.

Computational Geometry · Computer Science 2025-06-24 Joseph O'Rourke

We present two algorithms for unfolding the surface of any polyhedron, all of whose faces are triangles, to a nonoverlapping, connected planar layout. The surface is cut only along polyhedron edges. The layout is connected, but it may have…

Computational Geometry · Computer Science 2010-01-21 Erik D. Demaine , David Eppstein , Jeff Erickson , George W. Hart , Joseph O'Rourke

We show that four of the five Platonic solids' surfaces may be cut open with a Hamiltonian path along edges and unfolded to a polygonal net each of which can "zipper-refold" to a flat doubly covered parallelogram, forming a rather compact…

Computational Geometry · Computer Science 2010-10-21 Joseph O'Rourke

The notion of a spiral unfolding of a convex polyhedron, resulting by flattening a special type of Hamiltonian cut-path, is explored. The Platonic and Archimedian solids all have nonoverlapping spiral unfoldings, although among generic…

Computational Geometry · Computer Science 2015-10-20 Joseph O'Rourke

We present new examples of topologically convex edge-ununfoldable polyhedra, i.e., polyhedra that are combinatorially equivalent to convex polyhedra, yet cannot be cut along their edges and unfolded into one planar piece without overlap.…

Computational Geometry · Computer Science 2020-07-30 Erik D. Demaine , Martin L. Demaine , David Eppstein

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

Starting with the unsolved "D\"urer's problem" of edge-unfolding a convex polyhedron to a net, we specialize and generalize (a) the types of cuts permitted, and (b) the polyhedra shapes, to highlight both advances established and which…

Computational Geometry · Computer Science 2019-08-21 Joseph O'Rourke

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

It is shown that every orthogonal terrain, i.e., an orthogonal (right-angled) polyhedron based on a rectangle that meets every vertical line in a segment, has a grid unfolding: its surface may be unfolded to a single non-overlapping piece…

Computational Geometry · Computer Science 2007-07-12 Joseph O'Rourke

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 investigate how to make the surface of a convex polyhedron (a polytope) by folding up a polygon and gluing its perimeter shut, and the reverse process of cutting open a polytope and unfolding it to a polygon. We explore basic enumeration…

Computational Geometry · Computer Science 2007-05-23 Erik D. Demaine , Martin L. Demaine , Anna Lubiw , Joseph O'Rourke

An orthotube consists of orthogonal boxes (e.g., unit cubes) glued face-to-face to form a path. In 1998, Biedl et al. showed that every orthotube has a grid unfolding: a cutting along edges of the boxes so that the surface unfolds into a…

Computational Geometry · Computer Science 2023-05-02 Erik D. Demaine , Kritkorn Karntikoon

Over a decade ago, it was shown that every edge unfolding of the Platonic solids was without self-overlap, yielding a valid net. We consider this property for regular polytopes in arbitrary dimensions, notably the simplex, cube, and…

Computational Geometry · Computer Science 2021-11-03 Satyan L. Devadoss , Matthew Harvey

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

Ghomi proved that every convex polyhedron could be stretched via an affine transformation so that it has an edge-unfolding to a net [Gho14]. A net is a simple planar polygon; in particular, it does not self-overlap. One can view his result…

Computational Geometry · Computer Science 2023-02-17 Joseph O'Rourke

This note proves that every polar zonohedron has an edge-unfolding to a non-overlapping net.

Computational Geometry · Computer Science 2023-02-17 Joseph O'Rourke

An unfolding of a polyhedron is produced by cutting the surface and flattening to a single, connected, planar piece without overlap (except possibly at boundary points). It is a long unsolved problem to determine whether every polyhedron…

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

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

We show that every orthogonal polyhedron homeomorphic to a sphere can be unfolded without overlap while using only polynomially many (orthogonal) cuts. By contrast, the best previous such result used exponentially many cuts. More precisely,…

Computational Geometry · Computer Science 2011-12-21 Mirela Damian , Erik Demaine , Robin Flatland

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
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