# Quickie

One other quick item from Eureka, the journal of the Cambridge University Mathematical Society:

In its 1947 problem drive, the society proposed the following problem:

To find unequal positive integers x, y, z such that

x3 + y3 = z4.

“Although there were some research students in Theory of Numbers among those who tried, not one person succeeded in solving it within the time, yet the solution is extremely simple.” What is it?

# Podcast Episode 348: Who Killed the Red Baron?

In 1918, German flying ace Manfred von Richthofen chased an inexperienced Canadian pilot out of a dogfight and up the Somme valley. It would be the last chase of his life. In this week’s episode of the Futility Closet podcast we’ll describe the last moments of the Red Baron and the enduring controversy over who ended his career.

We’ll also consider some unwanted name changes and puzzle over an embarrassing Oscar speech.

See full show notes …

# A Plate of 1,000 Cookies

A puzzle by David B., a mathematician at the National Security Agency, from the agency’s May 2017 Puzzle Periodical:

Steve, Tony, and Bruce have a plate of 1,000 cookies to share. They decide to share them in the following way: beginning with Steve, each of them in turn takes as many cookies as he likes (they must take an integer amount, greater than or equal to 1), and then passes the plate clockwise (with Tony sitting to Steve’s left, and Bruce sitting to Tony’s left). Nobody wants to feel like he hogged too many cookies, so they all want to avoid being the player at the end who has taken the most cookies. Additionally, nobody wants to feel cheated by finishing with the fewest cookies. Finally, given that the previous two conditions are definitely met, or definitely cannot be met, each player would like to maximize the number of cookies he eats. The players’ objectives can be summarized as follows:

Objectives:

1. Have one player who has eaten more cookies than you, and one player who has eaten fewer cookies than you.
2. Eat as many cookies as possible.

Objective #1 takes infinite priority over Objective #2. Assuming that all players are perfectly rational, that they are all aware of each other’s rationality and objectives, and that they cannot communicate with each other in any way, how many cookies should Steve take to ensure he meets both objectives and how many cookies will Tony and Bruce take if Steve takes the winning amount?

# Wanderlust

A raindrop that falls in Erie County, Pa., will travel 2,147 miles to the Gulf of Mexico rather than 15 miles to Lake Erie.

Via MapPorn. River Runner will trace any drop falling in the contiguous United States.

# Extended Engagement

The upper edge of the setting sun is sometimes seen to take on a green tinge, an effect of atmospheric refraction. Normally this is apparent only briefly, but for Richard Byrd’s Antarctic expedition of 1928-1930 it lasted more than half an hour:

Here the sun descends so slowly that it seems to roll along the horizon and as it will be only two days until it is above the horizon all the time for the rest of the summer it clings interminably before, with seeming reluctance, dropping from sight. As its downward movement is so prolonged the last rays shimmer above the barrier edge as it moves eastward, appearing and reappearing from behind the irregularities of the barrier surface. It trembles and pulsates, producing a vibration light of great beauty.

The night the green flash was seen some one ran into the administration building and called, ‘Come out and see the green sun.’

There was a rush for the surface and as eyes turned southward, they saw a tiny but brilliant green spot where the last ray of the upper limb of the sun hung on the skyline. It lasted an appreciable length of time, several seconds at least, and no sooner disappeared than it flashed forth again. Altogether it remained on the horizon with short interruptions for thirty-five minutes.

When it disappeared momentarily it seemed to have been shut off by a tiny spurt, an inequality in the skyline caused by the barrier surface.

“Even by moving the head up a few inches it would disappear and reappear again and after it had finally disappeared from view it could be recaptured by climbing up the first few steps of the [antenna] post.”

(From an account by witness Russell Owen, San Francisco Chronicle, Oct. 23, 1929.)

The Cook, a reversible portrait by Italian painter Giuseppe Arcimboldo, circa 1570.

Arcimboldo made a whole series of such paintings.

# Thomsen’s Theorem

Draw a triangle, pick a point on one side, and draw a path as shown, with each segment parallel to a side of the triangle.

Discovered by German mathematician Gerhard Thomsen.

# Public Spirit

The Guinness record for the most fraudulent election ever reported belongs to the Liberian general election of 1927, in which President Charles D.B. King was re-elected over challenger Thomas J. Faulkner:

 Candidate Votes % Charles D.B. King 243,000 96.43 Thomas J. Faulkner 9,000 3.57 Total 252,000 100.00

As there were fewer than 15,000 registered voters, this represents a turnout of 1,680 percent — robust indeed.

# Evolution

I just ran across this anecdote by Jason Rosenhouse in Notices of the American Mathematical Society. In a middle-school algebra class Rosenhouse’s brother was given this problem:

There are some horses and chickens in a barn, fifty animals in all. Horses have four legs while chickens have two. If there are 130 legs in the barn, then how many horses and how many chickens are there?

The normal solution is straightforward, but Rosenhouse’s brother found an alternative that’s even easier: “You just tell the horses to stand on their hind legs. Now there are fifty animals each with two legs on the ground, accounting for one hundred legs. That means there are thirty legs in the air. Since every horse has two legs in the air, we find that there are fifteen horses, and therefore thirty-five chickens.”

(Jason Rosenhouse, “Book Review: Bicycle or Unicycle?: A Collection of Intriguing Mathematical Puzzles,” Notices of the American Mathematical Society, 67:9 [October 2020], 1382-1385.)

# “Fermat’s Last Theorem”

A puzzle by H.A. Thurston, from the April 1947 issue of Eureka, the journal of recreational mathematics published at Cambridge University: