Geometry and Topology Commons^™

Grid Vertex-Unfolding Orthogonal Polyhedra, Mirela Damian

Computer Science: Faculty Publications

No abstract provided.

A Class Of Convex Polyhedra With Few Edge Unfoldings, Alex Benton, Joseph O'Rourke

Computer Science: Faculty Publications

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 have (several) nonoverlapping edge unfoldings.

Intrinsic Linking And Knotting Are Arbitrarily Complex, Erica Flapan, Blake Mellor, Ramin Naimi

Pomona Faculty Publications and Research

We show that, given any n and alpha, any embedding of any sufficiently large complete graph in R³ contains an oriented link with components Q₁,...,Q_n such that for every i not equal to j, Ilk(Q_i,Q_j)I greater than or equal to alpha and la₂(Q_i)l greater than or equal to alpha, where a₂(Q_i) denotes the second coefficient of the Conway polynomial of Q_i.

Foundations Of Geometry, Lawrence Michael Clarke

Theses Digitization Project

In this paper, a brief introduction to the history, and development of Euclidean geometry will be followed by a biographical background of David Hilbert, highlighting significant events in his educational and professional life. In an attempt to add rigor to the presentation of geometry, Hilbert defined concepts and presented five groups of axioms that were mutually independent yet compatible, including introducing axioms of congruence in order to present displacement.

Tessellations Of The Hyperbolic Plane, Roberto Carlos Soto

Theses Digitization Project

In this thesis, the two models of hyperbolic geometry, properties of hyperbolic geometry, fundamental regions created by Fuchsian groups, and the tessellations that arise from such groups are discussed.

The Eight Monarchs (Some Mathematical Magic), Jeremiah Farrell, Eric Nelson

Scholarship and Professional Work - LAS

The eight Monarchs are the four Kings and four Queens of an ordinary deck of cards. We can perform our magic without a deck by using the grid below with the K-Q token ( a coin can be used instead if one wishes).

The Effect: The magician's back will be turned while Mark, the subject, places the token on one of the suit nodes. Mark is to remember this starting position. Then Mark makes a sequence of moves; a move being one of four possibilities: a horizontal move, a vertical move, or a diagonal move to a new node or …

The Magic Octagon, Jeremiah Farrell, Tom Rodgers

Scholarship and Professional Work - LAS

The black nodes mark the corners of an octagon and each of these nodes in connected to four others by lines. The (rather hard) puzzle is to assign the sixteen numbers 0 through 15 to each of the sixteen lines so that each black node has a sum of 30 when the line numbers leading into it are added.

The word version of the puzzle was described in the article "Most-Perfect Word Magic", Oscar Thumpbindle, Word Ways Vol. 40(4). Nov. 2007.

The Magic Octahedron, Jeremiah Farrell

Scholarship and Professional Work - LAS

An octahedral die has several advantages over its cubic cousin, not the least of which is its ability to magically model a four dimensional tesseract. We will use a four coloring of the die to illustrate the magic.

Octahedral Dice, Todd Estroff, Jeremiah Farrell

Scholarship and Professional Work - LAS

All five Platonic solids have been used as random number generators in games involving chance with the cube being the most popular. Martin Gardenr, in his article on dice (MG 1977) remarks: "Why cubical?... It is the easiest to make, its six sides accomodate a set of numbers neither too large nor too small, and it rolls easily enough but not too easily."

Gardner adds that the octahedron has been the next most popular as a randomizer. We offer here several problems and games using octahedral dice. The first two are extensions from Gardner's article. All answers will be given …

N-Linear Algebra Of Type Ii, Florentin Smarandache, W.B. Vasantha Kandasamy

Branch Mathematics and Statistics Faculty and Staff Publications

This book is a continuation of the book n-linear algebra of type I and its applications. Most of the properties that could not be derived or defined for n-linear algebra of type I is made possible in this new structure: n-linear algebra of type II which is introduced in this book. In case of n-linear algebra of type II, we are in a position to define linear functionals which is one of the marked difference between the n-vector spaces of type I and II. However all the applications mentioned in n-linear algebras of type I can be appropriately extended to …

Intrinsic Linking And Knotting Are Arbitrarily Complex, Erica Flapan, Blake Mellor, Ramin Naimi

Mathematics, Statistics and Data Science Faculty Works

We show that, given any n and α, every embedding of any sufficiently large complete graph in R³ contains an oriented link with components Q₁, ..., Q_n such that for every i≠j, $|\lk(Q_i,Q_j)|\geq\alpha$ and |a₂(Qi)|≥α, where a₂(Q_i) denotes the second coefficient of the Conway polynomial of Q_i.

Weight Systems For Milnor Invariants, Blake Mellor

Mathematics, Statistics and Data Science Faculty Works

We use Polyak's skein relation to give a new proof that Milnor's string link homotopy invariants are finite type invariants, and to develop a recursive relation for their associated weight systems. We show that the obstruction to the triviality of these weight systems is the presence of a certain kind of spanning tree in the intersection graph of a chord diagram.

Musical Actions Of Dihedral Groups, Alissa S. Crans, Thomas M. Fiore, Ramon Satyendra

Mathematics, Statistics and Data Science Faculty Works

The sequence of pitches which form a musical melody can be transposed or inverted. Since the 1970s, music theorists have modeled musical transposition and inversion in terms of an action of the dihedral group of order 24. More recently music theorists have found an intriguing second way that the dihedral group of order 24 acts on the set of major and minor chords. We illustrate both geometrically and algebraically how these two actions are {\it dual}. Both actions and their duality have been used to analyze works of music as diverse as Hindemith and the Beatles.

Optimal Packings Of Up To 6 Equal Circles On A Triangular Flat Torus, Anna Castelaz, William Dickinson, Daniel Guillot, Sandi Xhumari

Student Summer Scholars Manuscripts

How do you optimally pack equal circles into the standard triangular torus? In this paper, we proved the optimal packings of 1 through 6 equal circles. In order to do this we used techniques from graph theory and also mathematical softwares like Maple and LaTeX. I only worked on proving the optimal packing of 6 equal circles on this special container called the standard triangular torus. In addition, I also contributed in improving the previous proofs for 5 or less equal circles. The purpose of my research was to prove the best packing of 6 equal circles into this at …

A Fundamental Region On Two Copies Of The Hyperbolic Plane, Alyssa Jesse Soenksen

Honors Program Theses

Hyperbolic geometry is a beautiful, non-Euclidean space that hosts spectacular patterns and infinite designs. To learn about this space, this paper will focus on how linear fractional transformations act on this space and the patterns that reveal themselves. To expand on this, I will construct a fundamental domain under these mappings and explore the coding of closed geodesics on the fundamental domain, which requires an understanding of continued fractions. My research will then be applied to two copies of the hyperbolic plane. My goal is to understand fundamental regions in this space and eventually the geodesics.

This paper is intended …

Band Unfoldings And Prismatoids: A Counterexample, Joseph O'Rourke

Computer Science: Faculty Publications

This note shows that the hope expressed in [ADL+07]--that the new algorithm for edge-unfolding any polyhedral band without overlap might lead to an algorithm for unfolding any prismatoid without overlap--cannot be realized. A prismatoid is constructed whose sides constitute a nested polyhedral band, with the property that every placement of the prismatoid top face overlaps with the band unfolding.

Unfolding Restricted Convex Caps, Joseph O'Rourke

Computer Science: Faculty Publications

This paper details an algorithm for unfolding a class of convex polyhedra, where each polyhedron in the class consists of a convex cap over a rectangular base, with several restrictions: the cap’s faces are quadrilaterals, with vertices over an underlying integer lattice, and such that the cap convexity is "radially monotone," a type of smoothness constraint. Extensions of Cauchy’s arm lemma are used in the proof of non-overlap.

A Fixed Point Theorem For The Infinite-Dimensional Simplex, Douglas Rizzolo '08, Francis E. Su

All HMC Faculty Publications and Research

We define the infinite-dimensional simplex to be the closure of the convex hull of the standard basis vectors in R^∞, and prove that this space has the fixed point property: any continuous function from the space into itself has a fixed point. Our proof is constructive, in the sense that it can be used to find an approximate fixed point; the proof relies on elementary analysis and Sperner's lemma. The fixed point theorem is shown to imply Schauder's fixed point theorem on infinite-dimensional compact convex subsets of normed spaces.

A Complexification Of Rolle’S Theorem, J. P. Pemba, A. R. Davies, N. K. Muoneke

Applications and Applied Mathematics: An International Journal (AAM)

A new version of the classical Rolle’s theorem is proved for any complex-valued differentiable function of the complex variable on an open connected convex subset of the complex field. The associated Mean-Value theorem follows naturally. A few explicit illustrative examples are provided in the closing section of the paper.

Epsilon-Unfolding Orthogonal Polyhedra, Mirela Damian, Robin Flatland, Joseph O'Rourke

Computer Science: Faculty Publications

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 may be unfolded. Here we prove, via an algorithm, that every orthogonal polyhedron (one whose faces meet at right angles) of genus zero may be unfolded. Our cuts are not necessarily along edges of the polyhedron, but they are always parallel to polyhedron edges. For a polyhedron of n vertices, portions of the unfolding will be rectangular strips which, in the worst case, …

The Lsb Theorem Implies The Kkm Lemma, Gwen Spencer '05, Francis E. Su

All HMC Faculty Publications and Research

No abstract provided in this article.

Relationships Between Braid Length And The Number Of Braid Strands, Cornelia A. Van Cott

Mathematics

For a knot K, let ℓ(K,n) be the minimum length of an n–stranded braid representative of K. Fixing a knot K, ℓ(K,n) can be viewed as a function of n, which we denote by ℓK(n). Examples of knots exist for which ℓK(n) is a nonincreasing function. We investigate the behavior of ℓK(n), developing bounds on the function in terms of the genus of K. The bounds lead to the conclusion that for any knot K the function ℓK(n) is eventually stable. We study the stable behavior of ℓK(n), with stronger results for homogeneous knots. For knots of nine or fewer …

An Upperbound On The Ropelength Of Arborescent Links, Larry Andrew Mullins

Theses Digitization Project

This thesis covers improvements on the upperbounds for ropelength of a specific class of algebraic knots.

Minimal Surfaces, Maria Guadalupe Chaparro

Theses Digitization Project

The focus of this project consists of investigating when a ruled surface is a minimal surface. A minimal surface is a surface with zero mean curvature. In this project the basic terminology of differential geometry will be discussed including examples where the terminology will be applied to the different subjects of differential geometry. In addition the focus will be on a classical theorem of minimal surfaces referred to as the Plateau's Problem.

Tutte Polynomial In Knot Theory, David Alan Petersen

Theses Digitization Project

This thesis reviews the history of knot theory with an emphasis on the diagrammatic approach to studying knots. Also covered are the basic concepts and notions of graph theory and how these two fields are related with an example of a knot diagram and how to associate it to a graph.

A Model Of Dna Knotting And Linking, Erica Flapan, Dorothy Buck

Pomona Faculty Publications and Research

We present a model of how DNA knots and links are formed as a result of a single recombination event, or multiple rounds of (processive) recombination events, starting with an unknotted, unlinked, or a (2,m)-torus knot or link substrate. Given these substrates, according to our model all DNA products of a single recombination event or processive recombination fall into a single family of knots and links.

Removing Sets From Connected Spaces While Preserving Connectedness, Melvin Henriksen, Amir Nikou

All HMC Faculty Publications and Research

As per the title, the nature of sets that can be removed from a product of more than one connected, arcwise connected, or point arcwise connected spaces while preserving the appropriate kind of connectedness is studied. This can depend on the cardinality of the set being removed or sometimes just on the cardinality of what is removed from one or two factor spaces. Sometimes it can depend on topological properties of the set being removed or its trace on various factor spaces. Some of the results are complicated to prove while being easy to state. Sometimes proofs for different kinds …

A New Lower Bound On Guard Placement For Wireless Localization, Mirela Damian, Robin Flatland, Joseph O'Rourke, Suneeta Ramswami

Computer Science: Faculty Publications

The problem of wireless localization asks to place and orient stations in the plane, each of which broadcasts a unique key within a fixed angular range, so that each point in the plane can determine whether it is inside or outside a given polygonal region. The primary goal is to minimize the number of stations. In this paper we establish a lower bound of ⌊2n/3⌋−1 stations for polygons in general position, for the case in which the placement of stations is restricted to polygon vertices, improving upon the existing ⌈n/2⌉ lower bound.

On Groups Of Homological Dimension One, Jonathan Cornick

Publications and Research

It has been conjectured that the groups of homological dimension one are precisely the nontrivial locally free groups. Some algebraic, geometric and analytic properties of any potential counter example to the conjecture are discussed.

Conics In The Hyperbolic Plane, Trent Phillip Naeve

Theses Digitization Project

An affine transformation such as T(P)=Q is a locus of an affine conic. Any affine conic can be produced from this incidence construction. The affine type of conic (ellipse, parabola, hyperbola) is determined by the invariants of T, the determinant and trace of its linear part. The purpose of this thesis is to obtain a corresponding classification in the hyperbolic plane of conics defined by this construction.