The Carl B. Allendoerfer Award, established in 1976, is made to authors of expository articles published in *Mathematics Magazine*. Carl B. Allendoerfer, a distinguished mathematician at the University of Washington, served as president of the Mathematical Association of America, 1959-60. This is an award of $1,000. Up to two of these awards are given annually at the Summer Meeting of the Association.

## List of Recipients

## 2021

Nancy Ho, James Godzik, Jennifer Jones, Thomas W. Mattman, and Dan Sours

Invisible Knots and Rainbow Rings: Knots Not Determined by Their Determinants

*Mathematics Magazine*, Vol. 93, no. 1, pp. 4-18.

DOI: 10.1080/0025570X.2020.1685320

Jocelyn R. Bell and Frank Wattenberg

The Slippery Duck Theorem

*Mathematics Magazine*, Vol. 93, no. 2, pp. 91-103.

DOI: 10.1080/0025570X.2020.1708693

## 2020

Beth Malmskog and Kathryn Haymaker

What (Quilting) Circles Can Be Squared?

*Mathematics Magazine*, Vol. 92, no. 3, June 2019, pp. 173-186.

Juan Arias de Reyna, David Clark, and Noam Elkies

A Modern Solution to the Gion Shrine Problem

*Mathematics Magazine*, Vol. 92, no. 2, March 2019, pp. 110-122.

## 2019

William Dunham

The Early (and Peculiar) History of the Möbius Function

*Mathematics Magazine*, Vol. 91, no. 2, March 2018, pp. 83-91.

Jordan Bell and Viktor Blåsjö

Pietro Mengoli’s 1650 Proof that the Harmonic Series Diverges

*Mathematics Magazine*, Vol. 91, no. 5, December 2018, pp. 341-347.

## 2018

Fumiko Futamura and Robert Lehr

A New Perspective on Finding the Viewpoint

*Mathematics Magazine*, Vol. 90, no. 4, October 2017, pp. 267-277.

## 2017

Brian Conrey, James Gabbard, Katie Grant, Andrew Liu, and Kent Morrison

Intransitive Dice

*Mathematics Magazine*, Vol. 89, no. 2, April 2016, pp. 133-143

Vladimir Pozdnyakov and Michael Steele

Buses, Bullies, and Bijections

*Mathematics Magazine*, Vol. 89, no. 3, June 2016, pp. 167-176

## 2016

Julia Barnes, Clinton Curry, Elizabeth Russell, and Lisbeth Schaubroeck

Emerging Julia Sets

*Mathematics Magazine*, Vol. 88, no. 2, April 2015

Irl Bivens and Ben Klein

The Median Value of a Continuous Function

*Mathematics Magazine*, Vol. 88, no. 1, February 2015

## 2015

Daniel Heath

Straightedge and Compass Constructions in Spherical Geometry

*Mathematics Magazine*, Vol. 87, no. 5, December 2014, pp. 350-359.

Andrew Beveridge and Stan Wagon

The Sorting Hat Goes to College

*Mathematics Magazine*, Vol. 87, no. 4, October 2014, pp. 243-251.

## 2014

Sally Cockburn and Joshua Lesperance

Deranged Socks

*Mathematics Magazine*, Vol. 86, no. 2, April 2013, pp. 97-109.

Susan Marshall and Donald Smith

Feedback, Control, and Distribution of Prime Numbers

*Mathematics Magazine*, Vol. 86, no. 3, June 2013, pp. 189-203.

## 2013

Khristo N. Boyadzhiev

Close Encounters with the Stirling Numbers of the Second Kind

*Mathematics Magazine*, Vol. 85, no. 4, October 2012, pp. 252-266

Adrian Rice and Ezra Brown

Why Ellipses Are Not Elliptic Curves

*Mathematics Magazine*, Vol. 85, no. 3, June 2012, pp. 163-176

## 2012

P. Mark Kayll

Integrals Don't Have Anything to Do with Discrete Math, Do They?

*Mathematics Magazine*, Vol. 84, no. 2, April 2011, pp. 108-119

John A. Adam

Blood Vessel Branching: Beyond the Standard Calculus Problem

*Mathematics Magazine*, Vol. 84, no. 3, April 2011, pp. 196-207

## 2011

Curtis D. Bennett, Blake Mellor, and Patrick Shanahan

Drawing a Triangle on the Thurston Model of Hyperbolic Space

*Mathematics Magazine*, Vol. 83, no. 2, April 2010, pp. 83-99

Gene Abrams and Jessica Sklar

The Graph Menagerie: Abstract Algebra and the Mad Veterinarian

*Mathematics Magazine*, Vol. 83, no. 3, April 2010, pp. 168-179

## 2010

Ezra Brown and Keith Mellinger

Kirkman's Schoolgirls Wearing Hats and Walking Through Fields of Numbers

*Mathematics Magazine*, Vol. 82, no. 1, February 2009, pp. 3-15

David Speyer and Bernd Sturmfels

Tropical Mathematics

*Mathematics Magazine*, Vol. 82, no. 3, June 2009, pp. 163-173

## 2009

Vesna Stojanoska and Orlin Stoytchev

Touching the Z2 in Three-Dimensional Rotations

*Mathematics Magazine*, Vol. 81, no. 5, December 2008, pp. 345-357

Jeff Suzuki

A Brief History of Impossibility

*Mathematics Magazine*, Vol. 81, no. 1, February 2008, pp. 27-38

## 2008

Eugene Boman, Richard Brazier, and Derek Seiple

Mom! There's an Astroid in My Closet!

*Mathematics Magazine*, Vol. 80 (2007), pp. 104-111

Chris Christensen

Polish Mathematicians Finding Patterns in Enigma Messages

*Mathematics Magazine*, Vol. 80 (2007), pp. 247-273

## 2007

Carl V. Lutzer

Hammer Juggling, Rotational Instability, and Eigenvalues

*Mathematics Magazine*, Vol. 79 (2006), pp. 243-250

Saul Stahl

The Evolution of the Normal Distribution

*Mathematics Magazine*, Vol. 79 (2006), pp. 96-113

## 2006

Robb T. Koether and John K. Osinach, Jr.

Outwitting the Lying Oracle

*Mathematics Magazine*, Vol. 78 (2005), pp. 98-109

Jeff Suzuki

The Lost Calculus (1637-1670): Tangency and Optimization without Limits

*Mathematics Magazine*, Vol. 78 (2005), pp. 339-353

## 2005

Roger B. Eggleton and William P. Galvin

Upper Bounds on the Sum of Principal Divisors of an Integer

*Mathematics Magazine*, Vol. 77 (2004), pp. 190-200

## 2004

Charles I. Delman and Gregory Galperin

A Tale of Three Circles

*Mathematics Magazine*, Vol. 76 (2003), pp. 15-32

## 2003

Dan Kalman

Doubly Recursive Multivariate Automatic Differentiation

*Mathematics Magazine*, Vol. 75 (2002), pp. 187-202

Ezra Brown

The Many Names of (7,3,1)

*Mathematics Magazine*, Vol. 75 (2002), pp. 83-94

## 2002

Mark McKinzie and Curtis Tuckey

Higher Trigonometry, Hyperreal Numbers, and Euler's Analysis of Infinities

*Mathematics Magazine*, Vol. 74 (2001), pp. 339-368

## 2001

Raphael Falk Jones and Janice L. Pearce

A Postmodern View of Fractions and the Reciprocals of Fermat Primes

*Mathematics Magazine*, Vol. 73 (2000), pp. 83-97

James N. Brawner

Dinner, Dancing, and Tennis, Anyone?

*Mathematics Magazine*, Vol. 73 (2000), pp. 29-36

## 2000

Donald Teets and Karen Whitehead

The Discovery of Ceres: How Gauss Became Famous

*Mathematics Magazine*, Vol. 72 (1999), pp. 83-91

## 1999

Victor Klee and John R. Reay

A Surprising but Easily Proved Geometric Decomposition Theorem

*Mathematics Magazine*, Vol. 71 (1998), pp. 3-11

Donald G. Saari and Fabrice Valognes

Geometry, Voting, and Paradoxes

*Mathematics Magazine*, Vol. 71 (1998), pp. 243-259

## 1998

Dan Kalman, Robert Mena, and Shahriar Shahriari

Variations on an Irrational Theme-Geometry, Dynamics, Algebra

*Mathematics Magazine*, Vol. 70 (1997), pp. 93-104

## 1997

Colm Mulcahy

Plotting and Scheming with Wavelets

*Mathematics Magazine*, Vol. 69 (1996), pp. 323-343

Lin Tan

The Group of Rational Points on the Unit Circle

*Mathematics Magazine*, Vol. 69 (1996), pp. 163-171

## 1996

Judith Grabiner

Descartes and Problem-Solving

*Mathematics Magazine*, Vol. 68 (1995), pp. 83-97

Daniel J. Velleman and Gregory S. Call

Permutations and Combination Locks

*Mathematics Magazine*, Vol. 68 (1995), pp. 243-253

## 1995

Lee Badger

Lazzarini's Lucky Approximation of pi

*Mathematics Magazine*, Vol. 67 (1994), pp. 83-91

Tristan Needham

The Geometry of Harmonic Functions

*Mathematics Magazine*, Vol. 67 (1994), pp. 92-108

## 1994

Joan Hutchinson

Coloring Ordinary Maps, Maps of Empires, and Maps of the Moon

*Mathematics Magazine*, Vol. 66 (1993), pp. 211-226

## 1993

Xun-cheng Huang

From Intermediate Value Theorem to Chaos

Mathematics Magazine, Vol. 65 (1992), pp. 91-103

## 1992

Israel Kleiner

Rigor and Proof in Mathematics: A Historical Perspective

*Mathematics Magazine*, Vol. 64 (1991), pp. 291-314

Gulbank D. Chakerian and David E. Logothetti

Cube Slices, Pictorial Triangles, and Probability

*Mathematics Magazine*, Vol. 64 (1991), pp. 219-241

## 1991

Ranjan Roy

The Discovery of the Series Formula for π by Leibniz, Gregory, and Nilakantha

*Mathematics Magazine*, Vol. 63 (1990), pp. 291-306

## 1990

Thomas Archibald

Connectivity and Smoke-Rings: Green's Second Identity in Its First Fifty Years

*Mathematics Magazine*, Vol. 62 (1989), pp. 219-232

Fan K. Chung, Martin Gardner, and Ronald L. Graham

Steiner Trees on a Checkerboard

*Mathematics Magazine*, Vol. 62 (1989), pp. 83-96

## 1989

W. B. Raymond Lickorish and Kenneth C. Millett

The New Polynomial Invariants of Knots and Links

*Mathematics Magazine*, Vol. 61 (1988), pp. 3-23

Judith V. Grabiner

The Centrality of Mathematics in the History of Western Thought

*Mathematics Magazine*, Vol. 61 (1988), pp. 220-230

## 1988

Bart Braden

Pólya's Geometric Picture of Complex Contour Integrals

*Mathematics Magazine*, Vol. 60 (1987), pp. 321-327

Steven Galovich

Products of Sines and Cosines

*Mathematics Magazine*, Vol. 60 (1987), pp. 105-113

## 1987

Israel Kleiner

The Evolution of Group Theory: A Brief Survey

*Mathematics Magazine*, Vol. 59 (1986), pp. 195-215

Paul Zorn

The Bieberbach Conjecture

*Mathematics Magazine*, Vol. 59 (1986), pp. 131-148

## 1986

Bart Braden

Design of an Oscillating Sprinkler

*Mathematics Magazine*, Vol. 58 (1985), pp. 29-38

Saul Stahl

The Other Map Coloring Theorem

*Mathematics Magazine*, Vol. 58 (1985), pp. 131-145

## 1985

Frederick S. Gass

Constructive Ordinal Notation Systems

*Mathematics Magazine*, Vol. 57 (1984), pp. 131-141

Philip D. Straffin, Jr. and Bernard Grofman

Parliamentary Coalitions: A Tour of Models

*Mathematics Magazine*, Vol. 57 (1984), pp. 259-274

## 1984

Judith V. Grabiner

The Changing Concept of Change: The Derivative from Fermat to Weierstrass

*Mathematics Magazine*, Vol. 56 (1983), pp. 195-206

## 1983

Donald O. Koehler

Mathematics and Literature

*Mathematics Magazine*, Vol. 55 (1982), pp. 81-95

Clifford H. Wagner

A Generic Approach to Iterative Methods

*Mathematics Magazine*, Vol. 55 (1982), pp. 259-273

## 1982

J. Ian Richards

Continued Fractions without Tears

*Mathematics Magazine*, Vol. 54 (1981), pp. 163-171

Marjorie Senechal

Which Tetrahedra Fill Space?

*Mathematics Magazine*, Vol. 54 (1981), pp. 227-243

## 1981

Stephen B. Maurer

The King Chicken Theorems

*Mathematics Magazine*, Vol. 53 (1980), pp. 67-80

Donald E. Sanderson

Advanced Plane Topology from an Elementary Standpoint

*Mathematics Magazine*, Vol. 53 (1980), pp. 81-89

## 1980

Victor L. Klee, Jr.

Some Unsolved Problems in Plane Geometry

*Mathematics Magazine*, Vol. 52 (1979), pp. 131-145

Ernst Snapper

The Three Crises in Mathematics: Logicism, Intuitionism, and Formalism

*Mathematics Magazine*, Vol. 52 (1979), pp. 207-216

## 1979

Bruce C. Berndt

Ramanujan's Notebooks

*Mathematics Magazine*, Vol. 51 (1978), pp. 147-164

Doris Schattschneider

Tiling the Plane with Congruent Pentagons

*Mathematics Magazine*, Vol. 51 (1978), pp. 29-44

## 1978

Geoffry C. Shephard and Branko Grünbaum

Tilings by Regular Polygons

*Mathematics Magazine*, Vol. 50 (1977), pp. 227-247

David A. Smith

Human Population Growth: Stability or Explosion?

*Mathematics Magazine*, Vol. 50 (1977), pp. 186-197

## 1977

Joseph A. Gallian

The Search for Finite Simple Groups

*Mathematics Magazine*, Vol. 49 (1976), pp. 163-180

B.L. van der Waerden

Hamilton's Discovery of Quaternions

*Mathematics Magazine*, Vol. 49 (1976), pp. 227-234