Bus Bunching

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Image: Wikimedia Commons

When two or more buses are scheduled at regular intervals on the same route, planners may expect that each will make the same progress, pausing at each stop for the same interval (1). But if Bus B is delayed by traffic congestion (2), it incurs a penalty: Because it arrives late to the next stop, it will pick up some passengers who’d planned to take Bus C (3). Accommodating these passengers delays Bus B even longer, putting it even further behind schedule. Meanwhile, Bus C begins to make unusually good progress (4), as it now arrives at each stop to find a smaller crowd than expected.

As the workload piles up on the foremost bus and the one behind it catches up, eventually the result (5) is that the two buses run in a platoon, arriving together at each stop. Sometimes Bus C even overtakes Bus B.

What to do? Planners can set minimum and maximum amounts of time to be spent at each stop, and buses might even be told to skip certain stops during crowded runs. Passengers might be encouraged to wait for a following bus, with the inducement that it’s less crowded. Northern Arizona University improved its service by abandoning the idea of a schedule altogether and delaying buses at certain stops in order to maintain even spacing. One thing that doesn’t work: adding vehicles to the route — which might, at first blush, have seemed the obvious solution.

Great and Small

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One could not think of Aristotle or Beethoven multiplying 3,472,701 by 99,999 without making a mistake, nor could one think of him remembering the range of this or that railway share for two years, or the number of ten-penny nails in a hundred weight, or the freight on lard from Galveston to Rotterdam. And by the same token one could not imagine him expert at billiards, or at grouse-shooting, or at golf, or at any other of the idiotic games at which what are called successful men commonly divert themselves. In his great study of British genius, Havelock Ellis found that an incapacity for such petty expertness was visible in almost all first rate men. They are bad at tying cravats. They do not understand the fashionable card games. They are puzzled by book-keeping. They know nothing of party politics. In brief, they are inert and impotent in the very fields of endeavour that see the average men’s highest performances, and are easily surpassed by men who, in actual intelligence, are about as far below them as the Simidae.

— H.L. Mencken, In Defense of Women, 1918

Odd Job

A problem by Russian mathematician Viktor Prasolov:

On a piece of graph paper, is it possible to paint 25 cells so that each of them has an odd number of painted neighbors? (“Neighboring” cells have a common side.)

Click for Answer

Worth Noting

In 1600, a woman named Mary Deane was imprisoned for adultery in London’s Bridewell Prison, where she communicated with her lover in a secret code she’d learned from her mother. Unable to break the cipher, the prison authorities arranged for her to be whipped and deported to Scotland.

I’ve confirmed just enough of this to be sure it happened, but I can’t find many more details, including (as I’d hoped) the code. Still, it’s a striking story.

Uh-Oh

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Image: Wikimedia Commons

This worrying result was first published by German mathematician Oskar Schlömilch in 1868. (The discrepancy is explained by minute gaps in the diagonals, as explained here.)

Charles Dodgson (Lewis Carroll) seems to have been taken with the paradox — his papers show that between 1890 and 1893 he was working to determine all the squares that might similarly be converted into rectangles with a “gain” of one unit of area, apparently unaware that V. Schlegel had carried out the same task much earlier.

(Warren Weaver, “Lewis Carroll and a Geometrical Paradox,” American Mathematical Monthly 45:4 [April 1938], 234-236.)

The Sure Thing

In a 1905 short story by Jacob Elson, Mr. Brown laments that he cannot solve chess problems.

Mr. Pincus wagers $10 that “I can show you a two-move problem with three different lines of play which you would have to solve whether you wanted to or not.”

Brown accepts. After studying the board for 10 minutes, he says, “It’s a humbug, a confounded silly swindling humbug, but I am beat.” Here’s the position:

sure thing chess position

Studies

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Image: Wikimedia Commons

This bookcase, in Bologna’s International Music Museum and Library, is itself a work of art — the doors are paintings depicting shelves of music books, rendered by Baroque artist Giuseppe Crespi.

Below: In 2014, designer József Páhy devised this bookish façade for a housing estate in Kazincbarcika, Northern Hungary. That’s a teddy bear on the bottom shelf.

Image: <a href="https://commons.wikimedia.org/wiki/File:Kazincbarcika,_Nagy_Lajos_%C3%BAt_14-18..JPG">Wikimedia Commons</a>
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Dispatches

“A Time-Series Analysis of My Girlfriend’s Mood Swings”

“Behavioral Conditioning Methods to Stop My Boyfriend From Playing The Witcher 3”

“Sub-Nyquist Sampling While Listening to My Girlfriend”

“Who Should Do the Dishes? A Transportation Problem Solution”

“Freudian Psychoanalysis of My Boyfriend’s Gun Collection”

“Breaking Up With Your Girlfriend but Not Your Friends: A Cyclic Graph Algorithm for Social Network Preservation”

“The Future of Romance: Novel Techniques for Replacing Your Boyfriend With Generative AI”

“Winning Tiffany Back: How to Defeat an AI Boyfriend”

“Would He Still Love Me as a Worm: Indirect Sampling and Inference Techniques for Romantic Assurance”

Via r/ImmaterialScience.

Escape

In 1 Samuel 23:7-13, man’s free will seems to undermine God’s omniscience:

7 And it was told Saul that David was come to Keilah. And Saul said, God hath delivered him into mine hand; for he is shut in, by entering into a town that hath gates and bars.
8 And Saul called all the people together to war, to go down to Keilah, to besiege David and his men.
9 And David knew that Saul secretly practised mischief against him; and he said to Abiathar the priest, Bring hither the ephod.
10 Then said David, O Lord God of Israel, thy servant hath certainly heard that Saul seeketh to come to Keilah, to destroy the city for my sake.
11 Will the men of Keilah deliver me up into his hand? will Saul come down, as thy servant hath heard? O Lord God of Israel, I beseech thee, tell thy servant. And the Lord said, He will come down.
12 Then said David, Will the men of Keilah deliver me and my men into the hand of Saul? And the Lord said, They will deliver thee up.
13 Then David and his men, which were about six hundred, arose and departed out of Keilah, and went whithersoever they could go. And it was told Saul that David was escaped from Keilah; and he forbare to go forth.

God has foretold David’s capture, but David escapes by fleeing the city.

Arguably, though, this only shows that God’s perfect knowledge extends to counterfactuals, especially those regarding human action.