Mathematical art and artistic mathematics

ABSTRACT

The purpose of this note is to describe the mathematics that emanates from the construction of an origami box. We first construct a simple origami box from two rectangular sheets and then discuss some of the mathematical questions that arise in the context of geometry and algebra.     

Origami,geometry and art

The purpose of this paper is to describe the mathematics that emanates from the construction of an origami box. We first construct a simple origami box from a rectangular sheet and then discuss some of the mathematical questions that arise in the context of geometry and algebra. The activity can be used as a context for illustrating how algebra and geometry, like other branches of mathematics, are interrelated.     

Using origami boxes to explore concepts of geometry and calculus

The purpose of this classroom note is to provide an example of how a simple origami box can be used to explore important concepts of geometry and calculus. This article describes how an origami box can be folded, then it goes on to describe how its volume and surface area can be calculated. Finally, it describes how the box could be folded to maximize the surface area and the volume.     

Toric origami manifolds and multi-fans

The notion of a toric origami manifold, which weakens the notion of a symplectic toric manifold, was introduced by A. Cannas da Silva, V. Guillemin and A.R. Pires. They showed that toric origami manifolds bijectively correspond to origami templates via moment maps, where an origami template is a collection of Delzant polytopes with some folding data. Like a fan is associated to a Delzant polytope, a multi-fan introduced by A. Hattori and M. Masuda can be associated to an oriented origami template. In this paper, we discuss their relationship and show that any simply connected compact smooth 4-manifold with a smooth action of T ² can be a toric origami manifold. We also characterize products of even dimensional spheres which can be toric origami manifolds.     

Equivariant Chern Classes of Orientable Toric Origami Manifolds∗

A toric origami manifold, introduced by Cannas da Silva, Guillemin and Pires, is a generalization of a toric symplectic manifold. For a toric symplectic manifold, its equivariant Chern classes can be described in terms of the corresponding Delzant polytope and the stabilization of its tangent bundle splits as a direct sum of complex line bundles. But in general a toric origami manifold is not simply connected, so the algebraic topology of a toric origami manifold is more difficult than a toric symplectic manifold. In this paper they give an explicit formula of the equivariant Chern classes of an oriented toric origami manifold in terms of the corresponding origami template. Furthermore, they prove the stabilization of the tangent bundle of an oriented toric origami manifold also splits as a direct sum of complex line bundles.     

Diamond折纸管状结构轴向冲击性能分析

为了降低薄壁管状结构受轴向冲击时的初始峰值载荷,将diamond刚性折纸模型引入到薄壁管状结构的设计中.利用有限元分析方法,以方形截面为例,分析了diamond折纸管状结构的轴向冲击性能.结果表明:相比于传统方形薄壁管,diamond折纸管状结构具有较低的初始峰值载荷和更加平稳的变形过程.得出了diamond折纸管状结构按折纸预折形式变形的临界条件.分析了diamond折纸管状结构在轴向冲击载荷作用下,底角对初始峰值载荷和平均冲击载荷的影响.     

Effect of inquiry-based instruction enriched with origami activities on achievement,and self-efficacy in geometry

The purpose of the study was to investigate the effect of inquiry-based instruction enriched with origami activities on 7th grade students’ achievement in reflection symmetry and self-efficacy in geometry. Two classes, instructed by the first author of the paper, were randomly assigned as experimental and control groups. In order to gather data, participants were administered Reflection Symmetry Achievement Test, and Geometry Self-Efficacy Scale as pre-test and post-test. The Analysis of Covariance was performed in order to answer the research questions. Moreover, five participants were interviewed to examine self-efficacy sources which are determinant of the change in self-efficacy levels. Findings revealed that the inquiry-based instruction enriched with origami activities had a significantly positive effect on students’ achievement in reflection symmetry and self-efficacy in geometry. Interviews showed that all four sources were influenced by the intervention.     

Realising countable groups as automorphisms of origamis on the Loch Ness monster

Archiv der Mathematik - It is known that every finite group can be represented as the full group of automorphisms of a suitable compact origami. In this paper, we provide a short argument to note...     

On the combinatorics of an origami model

We consider the problem of how the assembly process of an origami model, made up of similar pieces, can be completed given that at each step there are several choices. A result is given in the language of graphs that provides a sufficient condition under which assembly of the model will never fail.     

Normal origamis of Mumford curves

An origami (also known as square-tiled surface) is a Riemann surface covering a torus with at most one branch point. Lifting two generators of the fundamental group of the punctured torus decomposes the surface into finitely many unit squares. By varying the complex structure of the torus one obtains easily accessible examples of Teichmüller curves in the moduli space of Riemann surfaces. The p-adic analogues of Riemann surfaces are Mumford curves. A p-adic origami is defined as a covering of Mumford curves with at most one branch point, where the bottom curve has genus one. A classification of all normal non-trivial p-adic origamis is presented and used to calculate some invariants. These can be used to describe p-adic origamis in terms of glueing squares.     

Statistical modelling and repeatable structures: purpose,process and prediction

Children have limited exposure to statistical concepts and processes, yet researchers have highlighted multiple benefits of experiences in which they design and/or engage informally with statistical modelling. A study was conducted with a classroom in which students developed and utilised data-based models to respond to the inquiry question, Which origami animal jumps the furthest? The students used hat plots and box plots in Tinkerplots to make sense of variability in comparing distributions of their data and to support them to write justified conclusions of their findings. The study relied on classroom video and student artefacts to analyse aspects of the students’ modelling experiences which exposed them to powerful statistical ideas, such as key repeatable structures and dispositions in statistics. Three principles—purpose, process and prediction—are highlighted as ways in which the problem context, statistical structures and inquiry dispositions and cycle extended students’ opportunities to reason in sophisticated ways appropriate for their age. The research question under investigation was, How can an emphasis on purpose, process and prediction be implemented to support children’s statistical modelling? The principles illustrated in the study may provide a simple framework for teachers and researchers to develop statistical modelling practices and norms at the school level.     

Wrapping spheres with flat paper

We study wrappings of smooth (convex) surfaces by a flat piece of paper or foil. Such wrappings differ from standard mathematical origami because they require infinitely many infinitesimally small folds (“crumpling”) in order to transform the flat sheet into a surface of nonzero curvature. Our goal is to find shapes that wrap a given surface, have small area and small perimeter (for efficient material usage), and tile the plane (for efficient mass production). Our results focus on the case of wrapping a sphere. We characterize the smallest square that wraps the unit sphere, show that a 0.1% smaller equilateral triangle suffices, and find a 20% smaller shape contained in the equilateral triangle that still tiles the plane and has small perimeter.     

On box totally dual integral polyhedra

Edmonds and Giles introduced the class of box totally dual integral polyhedra as a generalization of submodular flow polyhedra. In this paper a geometric characterization of these polyhedra is given. This geometric result is used to show that each TDI defining system for a box TDI polyhedron is in fact a box TDI system, that the class of box TDI polyhedra is in co-NP and is closed under taking projections and dominants, that the class of box perfect graphs is in co-NP, and a result of Edmonds and Giles which is related to the facets of box TDI polyhdera.Supported by a grant from the Alexander von Humboldt-Stiftung.     

From virtual to physical reality with paper folding

Objects in a virtual world can be converted into hardcopy by perpendicular projection of each face onto a sheet of paper, cutting and gluing. Previously, use of this technique was restricted to a limited class of polyhedral objects. This paper extends this process to realistic virtual objects, with the traditional origami restriction of using only a single sheet of paper.A number of algorithms are explored to achieve this goal. The use of heuristics allows solutions to be found without exhaustive search of all possible layouts. Approaches to deal with pathological cases are described.The techniques have already been successfully applied to a number of complex models, selected from a number of model archives on the Internet.     

An interval version of separation by semispaces in max-min convexity

In this paper, we study separation of a closed box from a max-min convex set by max-min semispaces. This can be regarded as an interval extension of the known separation results. We give a constructive proof of the separation in the case when the box satisfies a certain condition, and we show that the separation is never possible when the condition is not satisfied. We also study the separation of two max-min convex sets by a box and by a box and a semispace.     

Box dimension of Neimark–Sacker bifurcation

In this article we show how a change of a box dimension of orbits of two-dimensional discrete dynamical systems is connected to their bifurcations in a non-hyperbolic fixed point. This connection is already shown in the case of one-dimensional discrete dynamical systems and Hopf bifurcation for continuous systems. Namely, at the bifurcation point the box dimension changes from zero to a certain positive value which is connected to the appropriate bifurcation. We study a two-dimensional discrete dynamical system with only one multiplier on the unit circle, and show a result for the box dimension of an orbit on the centre manifold. We also consider a planar discrete system undergoing a Neimark–Sacker bifurcation. It is shown that box dimension depends on the order of non-degeneracy at the non-hyperbolic fixed point and on the angle–displacement map. As it was expected, we prove that the box dimension is different in the rational and irrational case.     

Category and dimensions for cut-out sets

In this paper, we study the modified box dimensions of cut-out sets that belong to a positive, nonincreasing and summable sequence. Noting that the family of such sets is a compact metric space under the Hausdorff metric, we prove that the lower modified box dimension equals zero and the upper modified box dimension equals the upper box dimension for almost all cut-out set in the sense of Baire category.     

A comb of origami curves in the moduli space M 3 with three dimensional closure

The first part of this paper is a survey on Teichmüller curves and Veech groups, with emphasis on the special case of origamis where much stronger tools for the investigation are available than in the general case. In the second part we study a particular configuration of origami curves in genus 3: A “base” curve is intersected by infinitely many “transversal” curves. We determine their Veech groups and the closure of their locus in M ₃.      

Packing boxes with harmonic bricks

Given a box of integral dimensions and a supply of bricks all having the same integral dimensions, what is the largest number of bricks that can be packed in the box with the sides of the bricks parallel to the sides of the box? In this general form the question is very difficult. We can think of the box as being made up of unit cells and say that a set R of cells is a representing set for a brick of given dimensions provided every brick that can be placed in the box, sides parallel to the box, contains at least one of the cells in R. The maximum number of bricks that can be placed in the box is then less than or equal to the minimum cardinality of a representing set. In general, there is not equality. In the case of two dimensions and a harmonic brick, we prove there is equality always and exhibit a best packing. For three-dimensional boxes and a harmonic brick, there need not be equality. We derive several results which are of the nature that if certain inequalities relating the dimensions of the box and the brick are satisfied, then equality occurs. Our results are strong enough to imply, for example, that if the smallest face of the brick packs each face of the box perfectly, then there is equality. For a 1 × 2 × 4 brick, there is always equality if one of the dimensions of the box is even.