Popular Articles (Page 29)
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๐ Cleo, the mathematician that tricked Stack Exchange
Cleo was the pseudonym of an anonymous mathematician active on the mathematics Stack Exchange from 2013 to 2015, who became known for providing precise answers to complex mathematical integration problems without showing any intermediate steps. Due to the extraordinary accuracy and speed of the provided solutions, mathematicians debated whether Cleo was an individual genius, a collective pseudonym, or even an early artificial intelligence system.
During the poster's active period, Cleo posted 39 answers to advanced mathematical questions, primarily focusing on complex integration problems that had stumped other users. Cleo's answers were characterized by being consistently correct while providing no explanation of methodology, often appearing within hours of the original posts. The account claimed to be limited in interaction due to an unspecified medical condition.
The mystery surrounding Cleo's identity and mathematical abilities generated significant interest in the mathematical community, with users attempting to analyze solution patterns and writing style for clues. Some compared Cleo to historical mathematical figures like Srinivasa Ramanujan, known for providing solutions without conventional proofs. In 2025, Cleo was revealed to be Vladimir Reshetnikov, a software developer originally from Uzbekistan.
Discussed on
- "Cleo (Mathematician)" | 2026-10-06 | 256 Upvotes 58 Comments
- "Cleo, the mathematician that tricked Stack Exchange" | 2025-05-20 | 69 Upvotes 9 Comments
๐ Gall's Law
John Gall (September 18, 1925 โ December 15, 2014) was an American author and retired pediatrician. Gall is known for his 1975 book General systemantics: an essay on how systems work, and especially how they fail..., a critique of systems theory. One of the statements from this book has become known as Gall's law.
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- "Gall's Law" | 2019-03-19 | 329 Upvotes 101 Comments
๐ Idaho Stop
The Idaho stop is the common name for laws that allow cyclists to treat a stop sign as a yield sign, and a red light as a stop sign. It first became law in Idaho in 1982, but was not adopted elsewhere until Delaware adopted a limited stop-as-yield law, the "Delaware Yield", in 2017. Arkansas was the second state to legalize both stop-as-yield and red light-as-stop in April 2019. Studies in Delaware and Idaho have shown significant decreases in crashes at stop-controlled intersections.
Discussed on
- "Idaho Stop" | 2022-11-05 | 131 Upvotes 293 Comments
๐ Larry (Cat)
Larry (born c.โJanuary 2007) is a British domestic tabby cat who has served as Chief Mouser to the Cabinet Office at 10 Downing Street since 2011. He is cared for by Downing Street staff, and is not the personal property of the prime minister of the United Kingdom. Larry has lived at 10 Downing Street during the premierships of six prime ministers: David Cameron, Theresa May, Boris Johnson, Liz Truss, Rishi Sunak and Keir Starmer. He is the first cat to be officially given the title of Chief Mouser, according to the Downing Street government website.
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- "Larry (Cat)" | 2025-07-04 | 350 Upvotes 74 Comments
๐ Rue de L'Avenir
The Rue de l'Avenir (transl.โStreet of the future) was an electric moving walkway installed at the 1900 Exposition Universelle in Paris. It ran along the edge of the Exposition site, from the Esplanade of Les Invalides to the Champ de Mars, passing through nine stations along the way, where passengers could board. It was designed by architect Joseph Lyman Silsbee and engineer Max E. Schmidt, designers of The Great Wharf Moving Sidewalk installed at the 1893 World's Fair in Chicago, the first-ever moving walkway.
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- "Rue de L'Avenir" | 2024-01-05 | 295 Upvotes 118 Comments
๐ Boustrophedon
Boustrophedon (Ancient Greek: ฮฒฮฟฯ ฯฯฯฮฟฯฮทฮดฯฮฝ, boustrophฤdรณn "ox-turning" from ฮฒฮฟแฟฆฯ, bous, "ox", ฯฯฯฮฟฯฮฎ, strophฤ, "turn" and the adverbial suffix -ฮดฯฮฝ, "like, in the manner of"; that is, turning like oxen in ploughing) is a type of bi-directional text, mostly seen in ancient manuscripts and other inscriptions. Alternate lines of writing are flipped, or reversed, with reversed letters. Rather than going left-to-right as in modern European languages, or right-to-left as in Arabic and Hebrew, alternate lines in boustrophedon must be read in opposite directions. Also, the individual characters are reversed, or mirrored. It was a common way of writing in stone in Ancient Greece.
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- "Boustrophedon" | 2023-04-22 | 60 Upvotes 23 Comments
- "Boustrophedon" | 2017-10-24 | 82 Upvotes 59 Comments
- "Boustrophedon Order" | 2010-07-26 | 24 Upvotes 12 Comments
๐ Ship's cat
The ship's cat has been a common feature on many trading, exploration, and naval ships dating to ancient times. Cats have been carried on ships for many reasons, most importantly to control rodents. Vermin aboard a ship can cause damage to ropes, woodwork, and more recently, electrical wiring. Also, rodents threaten ships' stores, devour crews' foodstuff, and could cause economic damage to ships' cargo such as grain. They are also a source of disease, which is dangerous for ships that are at sea for long periods of time. Rat fleas are carriers of plague, and rats on ships were believed to be a primary vector of the Black Death.
Cats naturally attack and kill rodents, and their natural ability to adapt to new surroundings made them suitable for service on a ship. In addition, they offer companionship and a sense of home, security and camaraderie to sailors away from home.
Discussed on
- "Ship's cat" | 2014-03-03 | 277 Upvotes 72 Comments
๐ Non-transitive dice
A set of dice is nontransitive if it contains three dice, A, B, and C, with the property that A rolls higher than B more than half the time, and B rolls higher than C more than half the time, but it is not true that A rolls higher than C more than half the time. In other words, a set of dice is nontransitive if the binary relation โ X rolls a higher number than Y more than half the time โ on its elements is not transitive.
It is possible to find sets of dice with the even stronger property that, for each die in the set, there is another die that rolls a higher number than it more than half the time. Using such a set of dice, one can invent games which are biased in ways that people unused to nontransitive dice might not expect (see Example).
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- "Nontransitive Dice" | 2020-10-17 | 11 Upvotes 1 Comments
- "Nontransitive dice" | 2017-04-29 | 194 Upvotes 42 Comments
๐ IKEA Effect
The IKEA effect is a cognitive bias in which consumers place a disproportionately high value on products they partially created. The name derives from the name of Swedish manufacturer and furniture retailer IKEA, which sells many furniture products that require assembly.
The IKEA effect has been described as follows: "The price is low for IKEA products largely because they take labor out of the equation. With a Phillips screwdriver, an Allen wrench and rubber mallet, IKEA customers can very literally build an entire home's worth of furniture on a very tight budget. But what happens when they do?" They "fall in love with their IKEA creations. Even when there are parts missing and the items are incorrectly built, customers in the IKEA study still loved the fruits of their labors."
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- "IKEA Effect" | 2021-01-18 | 13 Upvotes 1 Comments
- "IKEA Effect" | 2017-12-30 | 256 Upvotes 118 Comments