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Ununfoldable Polyhedra with Convex Faces
Ununfoldable Polyhedra with Convex Faces Marshall Bern¤ Erik D. Demainey David Eppsteinz Eric Kuox Andrea Mantler{ Jack Snoeyink{ k Abstract Unfolding a convex polyhedron into a simple planar polygon is a well-studied prob- lem. In this paper, we study the limits of unfoldability by studying nonconvex poly- hedra with the same combinatorial structure as convex polyhedra. In particular, we give two examples of polyhedra, one with 24 convex faces and one with 36 triangular faces, that cannot be unfolded by cutting along edges. We further show that such a polyhedron can indeed be unfolded if cuts are allowed to cross faces. Finally, we prove that \open" polyhedra with triangular faces may not be unfoldable no matter how they are cut. 1 Introduction A classic open question in geometry [5, 12, 20, 24] is whether every convex polyhedron can be cut along its edges and flattened into the plane without any overlap. Such a collection of cuts is called an edge cutting of the polyhedron, and the resulting simple polygon is called an edge unfolding or net. While the ¯rst explicit description of this problem is by Shephard in 1975 [24], it has been implicit since at least the time of Albrecht Durer,Ä circa 1500 [11]. It is widely conjectured that every convex polyhedron has an edge unfolding. Some recent support for this conjecture is that every triangulated convex polyhedron has a vertex unfolding, in which the cuts are along edges but the unfolding only needs to be connected at vertices [10]. On the other hand, experimental results suggest that a random edge cutting of ¤Xerox Palo Alto Research Center, 3333 Coyote Hill Rd., Palo Alto, CA 94304, USA, email: [email protected]. -
On Speed: the Many Lives of Amphetamine
On Speed Nicolas Rasmussen On Speed The Many Lives of Amphetamine a New York University Press • New York and London NEW YORK UNIVERSITY PRESS New York and London www.nyupress.org © 2008 by New York University All rights reserved Library of Congress Cataloging-in-Publication Data Rasmussen, Nicolas, 1962– On speed : the many lives of amphetamine / Nicolas Rasmussen. p. ; cm. Includes bibliographical references and index. ISBN-13: 978-0-8147-7601-8 (cl : alk. paper) ISBN-10: 0-8147-7601-9 (cl : alk. paper) 1. Amphetamines—United States—History. 2. Amphetamine abuse— United States—History. I. Title. II. Title: Many lives of amphetamine. [DNLM: 1. Amphetamines—history—United States. 2. Amphetamine-Related Disorders—history—United States. 3. History, 20th Century—United States. 4. History, 21st Century—United States. QV 102 R225o 2007] RM666.A493R37 2007 362.29'90973—dc22 2007043261 New York University Press books are printed on acid-free paper, and their binding materials are chosen for strength and durability. Manufactured in the United States of America c10987654321 p10987654321 To my parents, Laura and Norman, for teaching me to ask questions Contents Acknowledgments ix Introduction 1 1 The New Sensation 6 2 Benzedrine: The Making of a Modern Medicine 25 3 Speed and Total War 53 4 Bootleggers, Beatniks, and Benzedrine Benders 87 5 A Bromide for the Atomic Age 113 6 Amphetamine and the Go-Go Years 149 7 Amphetamine’s Decline: From Mental Medicine to Social Disease 182 8 Fast Forward: Still on Speed, 1971 to Today 222 Conclusion: The Lessons of History 255 Notes 261 List of Archival Sources 347 Index 348 About the Author 352 Illustrations appear in two groups following pages 86 and 148. -
The Geometry Junkyard: Origami
Table of Contents Table of Contents 1 Origami 2 Origami The Japanese art of paper folding is obviously geometrical in nature. Some origami masters have looked at constructing geometric figures such as regular polyhedra from paper. In the other direction, some people have begun using computers to help fold more traditional origami designs. This idea works best for tree-like structures, which can be formed by laying out the tree onto a paper square so that the vertices are well separated from each other, allowing room to fold up the remaining paper away from the tree. Bern and Hayes (SODA 1996) asked, given a pattern of creases on a square piece of paper, whether one can find a way of folding the paper along those creases to form a flat origami shape; they showed this to be NP-complete. Related theoretical questions include how many different ways a given pattern of creases can be folded, whether folding a flat polygon from a square always decreases the perimeter, and whether it is always possible to fold a square piece of paper so that it forms (a small copy of) a given flat polygon. Krystyna Burczyk's Origami Gallery - regular polyhedra. The business card Menger sponge project. Jeannine Mosely wants to build a fractal cube out of 66048 business cards. The MIT Origami Club has already made a smaller version of the same shape. Cardahedra. Business card polyhedral origami. Cranes, planes, and cuckoo clocks. Announcement for a talk on mathematical origami by Robert Lang. Crumpling paper: states of an inextensible sheet. Cut-the-knot logo. -
A Survey of Folding and Unfolding in Computational Geometry
Combinatorial and Computational Geometry MSRI Publications Volume 52, 2005 A Survey of Folding and Unfolding in Computational Geometry ERIK D. DEMAINE AND JOSEPH O’ROURKE Abstract. We survey results in a recent branch of computational geome- try: folding and unfolding of linkages, paper, and polyhedra. Contents 1. Introduction 168 2. Linkages 168 2.1. Definitions and fundamental questions 168 2.2. Fundamental questions in 2D 171 2.3. Fundamental questions in 3D 175 2.4. Fundamental questions in 4D and higher dimensions 181 2.5. Protein folding 181 3. Paper 183 3.1. Categorization 184 3.2. Origami design 185 3.3. Origami foldability 189 3.4. Flattening polyhedra 191 4. Polyhedra 193 4.1. Unfolding polyhedra 193 4.2. Folding polygons into convex polyhedra 196 4.3. Folding nets into nonconvex polyhedra 199 4.4. Continuously folding polyhedra 200 5. Conclusion and Higher Dimensions 201 Acknowledgements 202 References 202 Demaine was supported by NSF CAREER award CCF-0347776. O’Rourke was supported by NSF Distinguished Teaching Scholars award DUE-0123154. 167 168 ERIKD.DEMAINEANDJOSEPHO’ROURKE 1. Introduction Folding and unfolding problems have been implicit since Albrecht D¨urer [1525], but have not been studied extensively in the mathematical literature until re- cently. Over the past few years, there has been a surge of interest in these problems in discrete and computational geometry. This paper gives a brief sur- vey of most of the work in this area. Related, shorter surveys are [Connelly and Demaine 2004; Demaine 2001; Demaine and Demaine 2002; O’Rourke 2000]. We are currently preparing a monograph on the topic [Demaine and O’Rourke ≥ 2005]. -
GEOMETRIC FOLDING ALGORITHMS I
P1: FYX/FYX P2: FYX 0521857570pre CUNY758/Demaine 0 521 81095 7 February 25, 2007 7:5 GEOMETRIC FOLDING ALGORITHMS Folding and unfolding problems have been implicit since Albrecht Dürer in the early 1500s but have only recently been studied in the mathemat- ical literature. Over the past decade, there has been a surge of interest in these problems, with applications ranging from robotics to protein folding. With an emphasis on algorithmic or computational aspects, this comprehensive treatment of the geometry of folding and unfolding presents hundreds of results and more than 60 unsolved “open prob- lems” to spur further research. The authors cover one-dimensional (1D) objects (linkages), 2D objects (paper), and 3D objects (polyhedra). Among the results in Part I is that there is a planar linkage that can trace out any algebraic curve, even “sign your name.” Part II features the “fold-and-cut” algorithm, establishing that any straight-line drawing on paper can be folded so that the com- plete drawing can be cut out with one straight scissors cut. In Part III, readers will see that the “Latin cross” unfolding of a cube can be refolded to 23 different convex polyhedra. Aimed primarily at advanced undergraduate and graduate students in mathematics or computer science, this lavishly illustrated book will fascinate a broad audience, from high school students to researchers. Erik D. Demaine is the Esther and Harold E. Edgerton Professor of Elec- trical Engineering and Computer Science at the Massachusetts Institute of Technology, where he joined the faculty in 2001. He is the recipient of several awards, including a MacArthur Fellowship, a Sloan Fellowship, the Harold E. -
© Cambridge University Press Cambridge
Cambridge University Press 978-0-521-85757-4 - Geometric Folding Algorithms: Linkages, Origami, Polyhedra Erik D. Demaine and Joseph O’Rourke Index More information Index 1-skeleton, 311, 339 bar, 9 3-Satisfiability, 217, 221 base, see origami, base, 2 α-cone canonical configuration, 151, 152 Bauhaus, 294 α-producible chain, 150, 151 Bellows theorem, 279, 348 δ-perturbation, 115 bending λ order function, 176, 177, 186 machine, xi, 13, 306 antisymmetry condition, 177, 186 pipe, 13, 14 consistency condition, 178, 186 sheet metal, 306 noncrossing condition, 179, 186 beta sheet, 158 time continuity, 174, 183, 187 Bezdek, Daniel, 331 transitivity condition, 178, 186 blooming, continuous, 333, 435 bond angle, 14, 131, 148, 151 Abe’s angle trisection, 286, 287 bond length, 148 accordion, 85, 193, 200, 261 active path, 244, 245, 247–249 cable, 53–55 acyclicity, 108 CAD, see cylindrical algebraic decomposition, 19 additor (Kempe), 32, 34, 35 cage, 21, 92, 93 Alexandrov, Aleksandr D., 348 canonical form, 74, 86, 87, 141, 151 Alexandrov’s theorem, 339, 348, 349, 352, 354, Cauchy’s arm lemma, 72, 133, 143, 145, 342, 343, 368, 381, 393, 419 377 existence, 351 Cauchy’s rigidity theorem, 43, 143, 213, 279, 339, uniqueness, 350 341, 342, 345, 348–350, 354, 403 algebraic motion, 107, 111 Cauchy—Steinitz lemma, 72, 342 algebraic set, 39, 44 chain algebraic variety, 27 4D, 92, 93, 437 alpha helix, 151, 157, 158 abstract, 65, 149, 153, 158 Amato, Nancy, 157 convex, 143, 145 amino acid, 158 cutting, xi, 91, 123 amino acid residue, 14, 148, 151 equilateral, see -
Marvelous Modular Origami
www.ATIBOOK.ir Marvelous Modular Origami www.ATIBOOK.ir Mukerji_book.indd 1 8/13/2010 4:44:46 PM Jasmine Dodecahedron 1 (top) and 3 (bottom). (See pages 50 and 54.) www.ATIBOOK.ir Mukerji_book.indd 2 8/13/2010 4:44:49 PM Marvelous Modular Origami Meenakshi Mukerji A K Peters, Ltd. Natick, Massachusetts www.ATIBOOK.ir Mukerji_book.indd 3 8/13/2010 4:44:49 PM Editorial, Sales, and Customer Service Office A K Peters, Ltd. 5 Commonwealth Road, Suite 2C Natick, MA 01760 www.akpeters.com Copyright © 2007 by A K Peters, Ltd. All rights reserved. No part of the material protected by this copyright notice may be reproduced or utilized in any form, electronic or mechanical, including photo- copying, recording, or by any information storage and retrieval system, without written permission from the copyright owner. Library of Congress Cataloging-in-Publication Data Mukerji, Meenakshi, 1962– Marvelous modular origami / Meenakshi Mukerji. p. cm. Includes bibliographical references. ISBN 978-1-56881-316-5 (alk. paper) 1. Origami. I. Title. TT870.M82 2007 736΄.982--dc22 2006052457 ISBN-10 1-56881-316-3 Cover Photographs Front cover: Poinsettia Floral Ball. Back cover: Poinsettia Floral Ball (top) and Cosmos Ball Variation (bottom). Printed in India 14 13 12 11 10 10 9 8 7 6 5 4 3 2 www.ATIBOOK.ir Mukerji_book.indd 4 8/13/2010 4:44:50 PM To all who inspired me and to my parents www.ATIBOOK.ir Mukerji_book.indd 5 8/13/2010 4:44:50 PM www.ATIBOOK.ir Contents Preface ix Acknowledgments x Photo Credits x Platonic & Archimedean Solids xi Origami Basics xii -
Make a Title
The Star Unfolding from a Geodesic Curve by Stephen Kiazyk A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master of Mathematics in Computer Science Waterloo, Ontario, Canada, 2014 c Stephen Kiazyk 2014 I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Abstract An unfolding of a polyhedron P is obtained by `cutting' the surface of P in such a way that it can be flattened into the plane into a single polygon. For most practical and theoretic applications, it is desirable for an algorithm to produce an unfolding which is simple, that is, non-overlapping. Currently, two methods for unfolding which guarantee non-overlap for convex polyhedra are known, the source unfolding, and the star unfolding. Both methods involve computing shortest paths from a single source point on the polyhedron's surface. In this thesis, we attempt to prove non-overlap of a variant called the geodesic star unfolding. This unfolding, much like the star unfolding, is computed by cutting shortest paths from each vertex to λ, a geodesic curve on the surface of a convex polyhedron P, and also cutting λ itself. Non-overlap of this case was conjectured by Demaine and Lubiw [15]. We are unsuccessful in completely proving non-overlap, though we present a number of partial results, and discuss some areas for future study. -
Bridges Stockholm 2018 Mathematics | Art | Music | Architecture | Education | Culture 2018 Conference Proceedings Editors
Bridges Stockholm 2018 Mathematics | Art | Music | Architecture | Education | Culture 2018 Conference Proceedings Editors Program Chairs Eve Torrence Bruce Torrence Department of Mathematics Department of Mathematics Randolph-Macon College Randolph-Macon College Ashland, Virginia, USA Ashland, Virginia, USA Short Papers Chair Workshop Papers Chair Carlo H. Séquin Kristóf Fenyvesi Computer Science Division Department of Music, Art and Culture Studies University of California University of Jyväskylä Berkeley, USA Jyväskylä, Finland Production Chair Craig S. Kaplan Cheriton School of Computer Science University of Waterloo Waterloo, Ontario, Canada Bridges Stockholm 2018 Conference Proceedings (www.bridgesmathart.org). All rights reserved. General permission is granted to the public for non-commercial reproduction, in limited quantities, of individual articles, provided authorization is obtained from individual authors and a complete reference is given for the source. All copyrights and responsibilities for individual articles in the 2018 Conference Proceedings remain under the control of the original authors. ISBN: 978-1-938664-27-4 ISSN: 1099-6702 Published by Tessellations Publishing, Phoenix, Arizona, USA (© 2018 Tessellations) Distributed by MathArtFun.com (mathartfun.com). Cover design: Margaret Kepner, Washington, DC, USA Bridges Organization Board of Directors Kristóf Fenyvesi George W. Hart Department of Music, Art and Culture Studies Stony Brook University University of Jyväskylä, Finland New York, USA Craig S. Kaplan Carlo H. -
What Is Mathematics, Really? Reuben Hersh Oxford University Press New
What Is Mathematics, Really? Reuben Hersh Oxford University Press New York Oxford -iii- Oxford University Press Oxford New York Athens Auckland Bangkok Bogotá Buenos Aires Calcutta Cape Town Chennai Dar es Salaam Delhi Florence Hong Kong Istanbul Karachi Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi Paris São Paolo Singapore Taipei Tokyo Toronto Warsaw and associated companies in Berlin Ibadan Copyright © 1997 by Reuben Hersh First published by Oxford University Press, Inc., 1997 First issued as an Oxford University Press paperback, 1999 Oxford is a registered trademark of Oxford University Press All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. Cataloging-in-Publication Data Hersh, Reuben, 1927- What is mathematics, really? / by Reuben Hersh. p. cm. Includes bibliographical references and index. ISBN 0-19-511368-3 (cloth) / 0-19-513087-1 (pbk.) 1. Mathematics--Philosophy. I. Title. QA8.4.H47 1997 510 ′.1-dc20 96-38483 Illustration on dust jacket and p. vi "Arabesque XXIX" courtesy of Robert Longhurst. The sculpture depicts a "minimal Surface" named after the German geometer A. Enneper. Longhurst made the sculpture from a photograph taken from a computer-generated movie produced by differential geometer David Hoffman and computer graphics virtuoso Jim Hoffman. Thanks to Nat Friedman for putting me in touch with Longhurst, and to Bob Osserman for mathematical instruction. The "Mathematical Notes and Comments" has a section with more information about minimal surfaces. Figures 1 and 2 were derived from Ascher and Brooks, Ethnomathematics , Santa Rosa, CA.: Cole Publishing Co., 1991; and figures 6-17 from Davis, Hersh, and Marchisotto, The Companion Guide to the Mathematical Experience , Cambridge, Ma.: Birkhauser, 1995. -
From Webspace to Cyberspace
From Webspace to Cyberspace Kevin Hughes Enterprise Integration Technologies July 1995 From Webspace to Cyberspace Version 1.0: December 1994 Version 1.1: July 1995 Copyright 1995 by Kevin Hughes The opinions stated in this document are solely those of the author and do not necessarily represent the views of Enterprise Integration Technologies. This document as a whole may be redistributed freely in any format for non-commercial purposes only. Comments, questions, corrections, and suggestions relating to this document are welcomed and can be sent to [email protected]. Trademarked names are used throughout this document; the trademark sym- bols have been omitted for editorial convenience with no intention of trade- mark infringement. Where such omissions exist the trademarked name has been printed with initial capitals. About the Author Kevin Hughes designs hypermedia products for EIT and is their webmaster. He has written Entering the World-Wide Web: A Guide to Cyberspace, an introduction to the World-Wide Web that has been used as training material in numerous companies and universities, and is a member of the World-Wide Web Hall of Fame. Enterprise Integration Technologies 800 El Camino Real Menlo Park, CA • 94025 Lobby: (415) 617-8000 Fax: (415) 617-8019 World-Wide Web: http://www.eit.com/ Thus science may implement the ways in which man produces, stores, and consults the record of the race. Vannevar Bush As We May Think Atlantic Monthly, July 1945 The trouble with the future is that it usually arrives when you least expect it. Arnold H. Glasow Foreword and Preface 5 of 254 Foreword and May 1993 was a quiet month, and it was business as usual on the Preface Internet. -
View This Volume's Front and Back Matter
I: Mathematics Koryo Miura Toshikazu Kawasaki Tomohiro Tachi Ryuhei Uehara Robert J. Lang Patsy Wang-Iverson Editors http://dx.doi.org/10.1090/mbk/095.1 6 Origami I. Mathematics AMERICAN MATHEMATICAL SOCIETY 6 Origami I. Mathematics Proceedings of the Sixth International Meeting on Origami Science, Mathematics, and Education Koryo Miura Toshikazu Kawasaki Tomohiro Tachi Ryuhei Uehara Robert J. Lang Patsy Wang-Iverson Editors AMERICAN MATHEMATICAL SOCIETY 2010 Mathematics Subject Classification. Primary 00-XX, 01-XX, 51-XX, 52-XX, 53-XX, 68-XX, 70-XX, 74-XX, 92-XX, 97-XX, 00A99. Library of Congress Cataloging-in-Publication Data International Meeting of Origami Science, Mathematics, and Education (6th : 2014 : Tokyo, Japan) Origami6 / Koryo Miura [and five others], editors. volumes cm “International Conference on Origami Science and Technology . Tokyo, Japan . 2014”— Introduction. Includes bibliographical references and index. Contents: Part 1. Mathematics of origami—Part 2. Origami in technology, science, art, design, history, and education. ISBN 978-1-4704-1875-5 (alk. paper : v. 1)—ISBN 978-1-4704-1876-2 (alk. paper : v. 2) 1. Origami—Mathematics—Congresses. 2. Origami in education—Congresses. I. Miura, Koryo, 1930– editor. II. Title. QA491.I55 2014 736.982–dc23 2015027499 Copying and reprinting. Individual readers of this publication, and nonprofit libraries acting for them, are permitted to make fair use of the material, such as to copy select pages for use in teaching or research. Permission is granted to quote brief passages from this publication in reviews, provided the customary acknowledgment of the source is given. Republication, systematic copying, or multiple reproduction of any material in this publication is permitted only under license from the American Mathematical Society.