The 10 Disjoint 24-Cells in the Two 600-Cells Making up the Gosset
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Uniform Polychora
BRIDGES Mathematical Connections in Art, Music, and Science Uniform Polychora Jonathan Bowers 11448 Lori Ln Tyler, TX 75709 E-mail: [email protected] Abstract Like polyhedra, polychora are beautiful aesthetic structures - with one difference - polychora are four dimensional. Although they are beyond human comprehension to visualize, one can look at various projections or cross sections which are three dimensional and usually very intricate, these make outstanding pieces of art both in model form or in computer graphics. Polygons and polyhedra have been known since ancient times, but little study has gone into the next dimension - until recently. Definitions A polychoron is basically a four dimensional "polyhedron" in the same since that a polyhedron is a three dimensional "polygon". To be more precise - a polychoron is a 4-dimensional "solid" bounded by cells with the following criteria: 1) each cell is adjacent to only one other cell for each face, 2) no subset of cells fits criteria 1, 3) no two adjacent cells are corealmic. If criteria 1 fails, then the figure is degenerate. The word "polychoron" was invented by George Olshevsky with the following construction: poly = many and choron = rooms or cells. A polytope (polyhedron, polychoron, etc.) is uniform if it is vertex transitive and it's facets are uniform (a uniform polygon is a regular polygon). Degenerate figures can also be uniform under the same conditions. A vertex figure is the figure representing the shape and "solid" angle of the vertices, ex: the vertex figure of a cube is a triangle with edge length of the square root of 2. -
Regular Polyhedra of Index 2
REGULAR POLYHEDRA OF INDEX 2 A dissertation presented by Anthony Cutler to The Department of Mathematics In partial fulfillment of the requirements for the degree of Doctor of Philosophy in the field of Mathematics Northeastern University Boston, Massachusetts April, 2009 1 REGULAR POLYHEDRA OF INDEX 2 by Anthony Cutler ABSTRACT OF DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mathematics in the Graduate School of Arts and Sciences of Northeastern University, April 2009 2 We classify all finite regular polyhedra of index 2, as defined in Section 2 herein. The definition requires the polyhedra to be combinatorially flag transitive, but does not require them to have planar or convex faces or vertex-figures, and neither does it require the polyhedra to be orientable. We find there are 10 combinatorially regular polyhedra of index 2 with vertices on one orbit, and 22 infinite families of combinatorially regular polyhedra of index 2 with vertices on two orbits, where polyhedra in the same family differ only in the relative diameters of their vertex orbits. For each such polyhedron, or family of polyhedra, we provide the underlying map, as well as a geometric diagram showing a representative face for each face orbit, and a verification of the polyhedron’s combinatorial regularity. A self-contained completeness proof is given. Exactly five of the polyhedra have planar faces, which is consistent with a previously known result. We conclude by describing a non-Petrie duality relation among regular polyhedra of index 2, and suggest how it can be extended to other combinatorially regular polyhedra. -
Report on the Comparison of Tesseract and ABBYY Finereader OCR Engines
IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands. Report on the comparison of Tesseract and ABBYY FineReader OCR engines Marcin Heliński, Miłosz Kmieciak, Tomasz Parkoła Poznań Supercomputing and Networking Center, Poland Table of contents 1. Introduction ............................................................................................................................ 2 2. Training process .................................................................................................................... 2 2.1 Tesseract training process ................................................................................................ 3 2.2 FineReader training process ............................................................................................. 8 3. Comparison of Tesseract and FineReader ............................................................................10 3.1 Evaluation scenario .........................................................................................................10 3.1.2 Evaluation criteria ......................................................................................................12 3.2. OCR recognition accuracy results ...................................................................................13 3.3 Comparison of Tesseract and FineReader recognition accuracy .....................................20 4 Conclusions ...........................................................................................................................23 -
1 Critical Noncolorings of the 600-Cell Proving the Bell-Kochen-Specker
Critical noncolorings of the 600-cell proving the Bell-Kochen-Specker theorem Mordecai Waegell* and P.K.Aravind** Physics Department Worcester Polytechnic Institute Worcester, MA 01609 *[email protected] ,** [email protected] ABSTRACT Aravind and Lee-Elkin (1998) gave a proof of the Bell-Kochen-Specker theorem by showing that it is impossible to color the 60 directions from the center of a 600-cell to its vertices in a certain way. This paper refines that result by showing that the 60 directions contain many subsets of 36 and 30 directions that cannot be similarly colored, and so provide more economical demonstrations of the theorem. Further, these subsets are shown to be critical in the sense that deleting even a single direction from any of them causes the proof to fail. The critical sets of size 36 and 30 are shown to belong to orbits of 200 and 240 members, respectively, under the symmetries of the polytope. A comparison is made between these critical sets and other such sets in four dimensions, and the significance of these results is discussed. 1. Introduction Some time back Lee-Elkin and one of us [1] gave a proof of the Bell-Kochen-Specker (BKS) theorem [2,3] by showing that it is impossible to color the 60 directions from the center of a 600- cell to its vertices in a certain way. This paper refines that result in two ways. Firstly, it shows that the 60 directions contain many subsets of 36 and 30 directions that cannot be similarly colored, and so provide more economical demonstrations of the theorem. -
Petrie Schemes
Canad. J. Math. Vol. 57 (4), 2005 pp. 844–870 Petrie Schemes Gordon Williams Abstract. Petrie polygons, especially as they arise in the study of regular polytopes and Coxeter groups, have been studied by geometers and group theorists since the early part of the twentieth century. An open question is the determination of which polyhedra possess Petrie polygons that are simple closed curves. The current work explores combinatorial structures in abstract polytopes, called Petrie schemes, that generalize the notion of a Petrie polygon. It is established that all of the regular convex polytopes and honeycombs in Euclidean spaces, as well as all of the Grunbaum–Dress¨ polyhedra, pos- sess Petrie schemes that are not self-intersecting and thus have Petrie polygons that are simple closed curves. Partial results are obtained for several other classes of less symmetric polytopes. 1 Introduction Historically, polyhedra have been conceived of either as closed surfaces (usually topo- logical spheres) made up of planar polygons joined edge to edge or as solids enclosed by such a surface. In recent times, mathematicians have considered polyhedra to be convex polytopes, simplicial spheres, or combinatorial structures such as abstract polytopes or incidence complexes. A Petrie polygon of a polyhedron is a sequence of edges of the polyhedron where any two consecutive elements of the sequence have a vertex and face in common, but no three consecutive edges share a commonface. For the regular polyhedra, the Petrie polygons form the equatorial skew polygons. Petrie polygons may be defined analogously for polytopes as well. Petrie polygons have been very useful in the study of polyhedra and polytopes, especially regular polytopes. -
Arxiv:1705.01294V1
Branes and Polytopes Luca Romano email address: [email protected] ABSTRACT We investigate the hierarchies of half-supersymmetric branes in maximal supergravity theories. By studying the action of the Weyl group of the U-duality group of maximal supergravities we discover a set of universal algebraic rules describing the number of independent 1/2-BPS p-branes, rank by rank, in any dimension. We show that these relations describe the symmetries of certain families of uniform polytopes. This induces a correspondence between half-supersymmetric branes and vertices of opportune uniform polytopes. We show that half-supersymmetric 0-, 1- and 2-branes are in correspondence with the vertices of the k21, 2k1 and 1k2 families of uniform polytopes, respectively, while 3-branes correspond to the vertices of the rectified version of the 2k1 family. For 4-branes and higher rank solutions we find a general behavior. The interpretation of half- supersymmetric solutions as vertices of uniform polytopes reveals some intriguing aspects. One of the most relevant is a triality relation between 0-, 1- and 2-branes. arXiv:1705.01294v1 [hep-th] 3 May 2017 Contents Introduction 2 1 Coxeter Group and Weyl Group 3 1.1 WeylGroup........................................ 6 2 Branes in E11 7 3 Algebraic Structures Behind Half-Supersymmetric Branes 12 4 Branes ad Polytopes 15 Conclusions 27 A Polytopes 30 B Petrie Polygons 30 1 Introduction Since their discovery branes gained a prominent role in the analysis of M-theories and du- alities [1]. One of the most important class of branes consists in Dirichlet branes, or D-branes. D-branes appear in string theory as boundary terms for open strings with mixed Dirichlet-Neumann boundary conditions and, due to their tension, scaling with a negative power of the string cou- pling constant, they are non-perturbative objects [2]. -
Regular Polyhedra Through Time
Fields Institute I. Hubard Polytopes, Maps and their Symmetries September 2011 Regular polyhedra through time The greeks were the first to study the symmetries of polyhedra. Euclid, in his Elements showed that there are only five regular solids (that can be seen in Figure 1). In this context, a polyhe- dron is regular if all its polygons are regular and equal, and you can find the same number of them at each vertex. Figure 1: Platonic Solids. It is until 1619 that Kepler finds other two regular polyhedra: the great dodecahedron and the great icosahedron (on Figure 2. To do so, he allows \false" vertices and intersection of the (convex) faces of the polyhedra at points that are not vertices of the polyhedron, just as the I. Hubard Polytopes, Maps and their Symmetries Page 1 Figure 2: Kepler polyhedra. 1619. pentagram allows intersection of edges at points that are not vertices of the polygon. In this way, the vertex-figure of these two polyhedra are pentagrams (see Figure 3). Figure 3: A regular convex pentagon and a pentagram, also regular! In 1809 Poinsot re-discover Kepler's polyhedra, and discovers its duals: the small stellated dodecahedron and the great stellated dodecahedron (that are shown in Figure 4). The faces of such duals are pentagrams, and are organized on a \convex" way around each vertex. Figure 4: The other two Kepler-Poinsot polyhedra. 1809. A couple of years later Cauchy showed that these are the only four regular \star" polyhedra. We note that the convex hull of the great dodecahedron, great icosahedron and small stellated dodecahedron is the icosahedron, while the convex hull of the great stellated dodecahedron is the dodecahedron. -
Convex Polytopes and Tilings with Few Flag Orbits
Convex Polytopes and Tilings with Few Flag Orbits by Nicholas Matteo B.A. in Mathematics, Miami University M.A. in Mathematics, Miami University A dissertation submitted to The Faculty of the College of Science of Northeastern University in partial fulfillment of the requirements for the degree of Doctor of Philosophy April 14, 2015 Dissertation directed by Egon Schulte Professor of Mathematics Abstract of Dissertation The amount of symmetry possessed by a convex polytope, or a tiling by convex polytopes, is reflected by the number of orbits of its flags under the action of the Euclidean isometries preserving the polytope. The convex polytopes with only one flag orbit have been classified since the work of Schläfli in the 19th century. In this dissertation, convex polytopes with up to three flag orbits are classified. Two-orbit convex polytopes exist only in two or three dimensions, and the only ones whose combinatorial automorphism group is also two-orbit are the cuboctahedron, the icosidodecahedron, the rhombic dodecahedron, and the rhombic triacontahedron. Two-orbit face-to-face tilings by convex polytopes exist on E1, E2, and E3; the only ones which are also combinatorially two-orbit are the trihexagonal plane tiling, the rhombille plane tiling, the tetrahedral-octahedral honeycomb, and the rhombic dodecahedral honeycomb. Moreover, any combinatorially two-orbit convex polytope or tiling is isomorphic to one on the above list. Three-orbit convex polytopes exist in two through eight dimensions. There are infinitely many in three dimensions, including prisms over regular polygons, truncated Platonic solids, and their dual bipyramids and Kleetopes. There are infinitely many in four dimensions, comprising the rectified regular 4-polytopes, the p; p-duoprisms, the bitruncated 4-simplex, the bitruncated 24-cell, and their duals. -
3D Visualization Models of the Regular Polytopes in Four and Higher Dimensions
BRIDGES Mathematical Connections in Art, Music, and Science 3D Visualization Models of the Regular Polytopes in Four and Higher Dimensions Carlo H. Sequin Computer Science Division, EECS Department University of California, Berkeley, CA 94720 E-maih [email protected] Abstract This paper presents a tutorial review of the construction of all regular polytopes in spaces of all possible dimensions . .It focusses on how to make instructive, 3-dimensional, physical visualization models for the polytopes of dimensions 4 through 6, using solid free-form fabrication technology. 1. Introduction Polytope is a generalization of the terms in the sequence: point, segment, polygon, polyhedron ... [1]. Such a polytope is called regular, if all its elements (vertices, edges, faces, cells ... ) are indistinguishable, i.e., if there exists a group of spatial transformations (rotations, mirroring) that will bring the polytope into coverage with itself. Through these symmetry operations, it must be possible to transform any particular element of the polytope into any other chosen element of the same kind. In two dimensions, there exist infinitely many regular polygons; the first five are shown in Figure 1. • • • Figure 1: The simplest regular 2D polygons. In three-dimensional space, there are just five regular polyhedra -- the Platonic solids, and they can readily be depicted by using shaded perspective renderings (Fig.2). As we contemplate higher dimensions and the regular polytopes that they may admit, it becomes progressively harder to understand the geometry of these objects. Projections down to two (printable) dimensions discard a fair amount of information, and people often have difficulties comprehending even 4D polytopes, when only shown pictures or 2D graphs. -
Introduction to Zome a New Language for Understanding the Structure of Space
Introduction to Zome A new language for understanding the structure of space Paul Hildebrandt Abstract This paper addresses some basic mathematical principles underlying Zome and the importance of numeracy in education. Zome geometry Zome is a new language for understanding the structure of space. In other words, Zome is “hands-on” math. Math has been called the “queen of the sciences,” and Zome’s simple elegance applies to every discipline represented at the Form conference. Zome balls and struts represent points and lines, and are designed to model the relationship between the numbers 2, 3, and 5 in space in a simple, intuitive way. There’s a relationship between the shape of a strut, its vector in space, its length and the number it represents. Shape – Each Zome strut represents a number. Notice that the blue strut has a cross-section of a golden rectangle -- the long sides are in the Divine Proportion to the short sides, i.e. if the length of the short side is 1 the long side is approximately 1.618. The rectangle has 2 short sides and 2 long sides, has 2-fold symmetry in 2 directions. Everything about the rectangle seems to be related to the number 2. If the blue strut represents the number 2, it makes sense that you can only build a square out of blue struts in Zome: the square has 2x2 edges, 2x2 corners and 2-fold symmetry along 2x2 axes. It seems that everything about the square is related to the number 2. What about the cube? Vector -- It seems logical that you must also build a cube with blue struts, since a cube is made out of squares. -
Zome and Euler's Theorem Julia Robinson Day Hosted by Google Tom Davis [email protected] April 23, 2008
Zome and Euler's Theorem Julia Robinson Day Hosted by Google Tom Davis [email protected] http://www.geometer.org/mathcircles April 23, 2008 1 Introduction The Zome system is a construction set based on a set of plastic struts and balls that can be attached together to form an amazing set of mathematically or artistically interesting structures. For information on Zome and for an on-line way to order kits or parts, see: http://www.zometool.com The main Zome strut colors are red, yellow and blue and most of what we’ll cover here will use those as examples. There are green struts that are necessary for building structures with regular tetrahedrons and octahedrons, and almost everything we say about the red, yellow and blue struts will apply to the green ones. The green ones are a little harder to work with (both physically and mathematically) because they have a pentagon-shaped head, but can fit into any pentagonal hole in five different orientations. With the regular red, yellow and blue struts there is only one way to insert a strut into a Zome ball hole. The blue- green struts are not really part of the Zome geometry (because they have the “wrong” length). They are necessary for building a few of the Archimedian solids, like the rhombicuboctahedron and the truncated cuboctahedron. For these exercises, we recommend that students who have not worked with the Zome system before restrict themselves to the blue, yellow and red struts. Students with some prior experience, or who seem to be very fast learners, can try building things (like a regular octahedron or a regular tetrahedron) with some green struts. -
Lesson Plans 1.1
Lesson Plans 1.1 © 2009 Zometool, Inc. Zometool is a registered trademark of Zometool Inc. • 1-888-966-3386 • www.zometool.com US Patents RE 33,785; 6,840,699 B2. Based on the 31-zone system, discovered by Steve Baer, Zomeworks Corp., USA www zometool ® com Zome System Table of Contents Builds Genius! Zome System in the Classroom Subjects Addressed by Zome System . .5 Organization of Plans . 5 Graphics . .5 Standards and Assessment . .6 Preparing for Class . .6 Discovery Learning with Zome System . .7 Cooperative vs Individual Learning . .7 Working with Diverse Student Groups . .7 Additional Resources . .8 Caring for your Zome System Kit . .8 Basic Concept Plans Geometric Shapes . .9 Geometry Is All Around Us . .11 2-D Polygons . .13 Animal Form . .15 Attention!…Angles . .17 Squares and Rectangles . .19 Try the Triangles . .21 Similar Triangles . .23 The Equilateral Triangle . .25 2-D and 3-D Shapes . .27 Shape and Number . .29 What Is Reflection Symmetry? . .33 Multiple Reflection Symmetries . .35 Rotational Symmetry . .39 What is Perimeter? . .41 Perimeter Puzzles . .43 What Is Area? . .45 Volume For Beginners . .47 Beginning Bubbles . .49 Rhombi . .53 What Are Quadrilaterals? . .55 Trying Tessellations . .57 Tilings with Quadrilaterals . .59 Triangle Tiles - I . .61 Translational Symmetries in Tilings . .63 Spinners . .65 Printing with Zome System . .67 © 2002 by Zometool, Inc. All rights reserved. 1 Table of Contents Zome System Builds Genius! Printing Cubes and Pyramids . .69 Picasso and Math . .73 Speed Lines! . .75 Squashing Shapes . .77 Cubes - I . .79 Cubes - II . .83 Cubes - III . .87 Cubes - IV . .89 Even and Odd Numbers . .91 Intermediate Concept Plans Descriptive Writing .