"How to Win at (One-Round) War" by Richard E. Chatwin and Dana Mackenzie, (September): two files (pdf).

Details of the proof of the optimal strategy

An alternative approach via a modified Hungarian algorithm

For "Parametric Flowers at the Circus: Trochoids and Poi Flowers" by Eleanor Farrington, (May): Explore changing frequencies of rotation or positions of the hands and poi (Geogebra file).

"Hyperbola: Under Construction!" by Mark Frantz, (November): Geometer's SketchPad files.

"On God’s Number(s) for Rubik’s Slide" by Michael A. Jones, Brittany Shelton, and Miriam Weaverdyck, (September): Rubik’s Slide Easy Graph and Rubik’s Slide Supplement.

"A Topological Definition of Limits for Use in Elementary Calculus" by Charles L. Cooper, (September): Topological Limits (pdf).

For "Locating Unimodular Roots" by Michael A. Brilleslyper and Lisbeth E. Schaubroeck, (May): This Mathematica notebook gives dynamic recreations of some results from the article and outlines explorations of additional related topics.

For "Integer Solutions to Box Optimization Programs" by Vincent Coll, Jeremy Davis, Martin Hall, Colton Magnant, James Stankewicz, and Hua Wang (May): The following Sage code generates rational solutions to the box problem described in the article. For more information, see stankewicz.net/

@interact

def _(n = 12):

assert type(n) == Integer

@interact(controls=[('m', slider(0,n,1,1))])

def _(**kwargs):

m = kwargs['m']

var("x y")

contour_plot.options["axes"]=

ell = implicit_plot(x^2 - x*y + y^2 ==1,(x,-2,2),(y,-2,2))

pt1 = point((-1,0),pointsize=80,

pt2 = point(((-(m/n)^2 + 1)/((m/n)^2 - (m/n) + 1),(-(m/n)^2 + 2*(m/n))/((m/n)^2 - (m/n) + 1)),pointsize=80,rgbcolor=(1,

pt3 = point((0,(m/n)),pointsize=80,

line = plot((m/n)*(x+1),(x,-2,2),

show(ell + pt1 + line + pt2 + pt3)

print "t = "+str(m/n)

print "x = "+str(n^2 - m^2)

print "y = "+str(2*m*n - m^2)

print "z = "+str(m^2 - m*n + n^2)

print "Roots = "+str((m*n - m^2)/2)+", "+str((2*n^2 + m*n - m^2)/6)

For "Collaborative Understanding of Cyanobacterial Growth in Lake Ecosystems" by Meredith Greer, Holly A. Ewing, Kathryn L. Cottingham, and Kathleen C. Weathers (November) Data for Gloeo Modeling (xlsx).

For Kenneth Schilling's "Derivative Sign Patterns in Two Dimensions" (March) Web Addendum (pdf).

For Timothy Jones' "Euler's Identity, Leibniz Tables and the Irrationality of Pi*"* (November): End Notes (pdf)

For Stephen M. Walk's "The Intermediate Value Theorem is NOT Obvious—and I AM Going to Prove It to You" (September): Proofs Leading to the Intermediate Value Theorem (pdf)

For Michael A. Jones' "Chutes and Ladders for the Impatient" (January), MAPLE file.

For Richard Kreminski's, "Taylor’s theorem: the elusive *c* is not so elusive" (May): Proofs of Theorems 2 and 3, plus other materials(pdf)

For Rick Mabry’s "The Hardest Straight-in Pool Shot" (January), proofs of all nine FACTS, written on napkins. Separate napkins (pdfs):

Facts 1-3

Fact 4

Fact 5

Fact 6

Fact 7

Fact 8

Fact 9

All the napkins in one wad: Facts 1-9

For Barry Cox and Stan Wagon’s "Mechanical Circle-Squaring" (September, pp 238-247), Mathematica generated simulations:

Geneva Drive Maltese Cross

Drilling a Square Hole

Drilling a Square Hole (Three Dimensions)

Drilling a Hexagonal Hole