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🔗 Mathematics

In the mathematical fields of set theory and extremal combinatorics, a sunflower or ${\displaystyle \Delta }$-system is a collection of sets whose pairwise intersection is constant. This constant intersection is called the kernel of the sunflower.

The main research question arising in relation to sunflowers is: under what conditions does there exist a large sunflower (a sunflower with many sets) in a given collection of sets? The ${\displaystyle \Delta }$-lemma, sunflower lemma, and the Erdős-Rado sunflower conjecture give successively weaker conditions which would imply the existence of a large sunflower in a given collection, with the latter being one of the most famous open problems of extremal combinatorics.

🔗 Economics

"The Market for Lemons: Quality Uncertainty and the Market Mechanism" is a well-known 1970 paper by economist George Akerlof which examines how the quality of goods traded in a market can degrade in the presence of information asymmetry between buyers and sellers, leaving only "lemons" behind. In American slang, a lemon is a car that is found to be defective after it has been bought.

Suppose buyers cannot distinguish between a high-quality car (a "peach") and a "lemon". Then they are only willing to pay a fixed price for a car that averages the value of a "peach" and "lemon" together (p_avg). But sellers know whether they hold a peach or a lemon. Given the fixed price at which buyers will buy, sellers will sell only when they hold "lemons" (since p_lemon < p_avg) and they will leave the market when they hold "peaches" (since p_peach > p_avg). Eventually, as enough sellers of "peaches" leave the market, the average willingness-to-pay of buyers will decrease (since the average quality of cars on the market decreased), leading to even more sellers of high-quality cars to leave the market through a positive feedback loop.

Thus the uninformed buyer's price creates an adverse selection problem that drives the high-quality cars from the market. Adverse selection is a market mechanism that can lead to a market collapse.

Akerlof's paper shows how prices can determine the quality of goods traded on the market. Low prices drive away sellers of high-quality goods, leaving only lemons behind. In 2001, Akerlof, along with Michael Spence, and Joseph Stiglitz, jointly received the Nobel Memorial Prize in Economic Sciences, for their research on issues related to asymmetric information.

🔗 Spaceflight 🔗 Moon 🔗 Rocketry 🔗 Solar System/Mars 🔗 Solar System

The SpaceX Starship is a fully-reusable launch vehicle and spacecraft that is being privately developed by SpaceX. It is designed to be a long-duration cargo and passenger-carrying spacecraft. The development of the Starship began in 2014.

🔗 Game theory

The pirate game is a simple mathematical game. It is a multi-player version of the ultimatum game.

🔗 Australia 🔗 New Zealand 🔗 Cricket 🔗 Australia/Australian sports 🔗 Cricket/EAP cricket

The underarm bowling incident of 1981 is a sporting controversy that took place on 1 February 1981, when Australia played New Zealand in a One Day International cricket match, the third in the best-of-five final of the 1980–81 World Series Cup, at the Melbourne Cricket Ground.

With one ball of the final over remaining in the match, New Zealand required a six to tie the match. To ensure that New Zealand were unable to achieve this, the Australian captain Greg Chappell instructed his bowler (and younger brother) Trevor Chappell to deliver the last ball to batsman Brian McKechnie underarm along the ground. Trevor did so, forcing McKechnie to play the ball defensively, meaning Australia won. This action, although legal at the time, was nevertheless widely perceived as being wholly against the traditional spirit of cricketing fair play.

The outrage caused by the incident eventually led to an official amendment to the international laws of cricket to prevent it from occurring again.

🔗 Mass surveillance 🔗 United Kingdom 🔗 Law Enforcement

🔗 Languages 🔗 Constructed languages

Ithkuil is an experimental constructed language created by John Quijada. It is designed to express deeper levels of human cognition briefly yet overtly and clearly, particularly with regard to human categorization. It is a cross between an a priori philosophical and a logical language. It tries to minimize the vagueness and semantic ambiguity found in natural human languages. Ithkuil is notable for its grammatical complexity and extensive phoneme inventory, the latter being simplified in an upcoming redesign. The name "Ithkuil" is an anglicized form of Iţkuîl, which in the original form roughly means "hypothetical representation of a language". Quijada states he did not create Ithkuil to be auxiliary or used in everyday conversations. He wanted the language to be used for more elaborate and profound fields where more insightful thoughts are expected, such as philosophy, arts, science and politics.

Meaningful phrases or sentences can usually be expressed in Ithkuil with fewer linguistic units than in natural languages. For example, the two-word Ithkuil sentence "Tram-mļöi hhâsmařpţuktôx" can be translated into English as "On the contrary, I think it may turn out that this rugged mountain range trails off at some point". Quijada deems his creation as too complex to have developed naturally, seeing it as an exercise in exploring how languages could function. No person, including Quijada himself, is known to be able to speak Ithkuil fluently. It was featured in the Language Creation Conference's 6th Conlang Relay.

Four versions of the language have been publicized: the initial version in 2004, a simplified version called Ilaksh in 2007, the current version in 2011, and as of 2017, various revisions of a new version of the language, named Ithkuil IV. In 2004—and again in 2009 with Ilaksh—Ithkuil was featured in the Russian-language popular science and IT magazine Computerra. In 2008, David Peterson awarded it the Smiley Award. In 2013, Bartłomiej Kamiński codified the language to be able to quickly parse complicated sentences. Julien Tavernier and anonymous others have followed suit. Since July 2015, Quijada has released several Ithkuil songs in a prog rock style as part of the album Kaduatán, which translates to "Wayfarers". Recently, online communities for the language have developed in English, Russian, Mandarin, and Japanese.

🔗 Russia 🔗 Internet culture 🔗 Military history 🔗 Europe 🔗 Politics 🔗 Sociology 🔗 Ukraine 🔗 Military history/Russian, Soviet and CIS military history 🔗 European history 🔗 Military history/Military culture, traditions, and heraldry

"Z" is one of several symbols painted on military vehicles of the Russian Armed Forces involved in the 2022 Russian invasion of Ukraine.

The symbol has been used in Russian popular culture as a sign of support for the invasion. Displaying any of the symbols on vehicles in public is illegal in Kazakhstan.

🔗 Religion 🔗 Classical Greece and Rome 🔗 Mythology

Glycon (Ancient Greek: Γλύκων Glýkōn, gen: Γλύκωνος Glýkōnos), also spelled Glykon, was an ancient snake god. He had a large and influential cult within the Roman Empire in the 2nd century, with contemporary satirist Lucian providing the primary literary reference to the deity. Lucian claimed Glycon was created in the mid-2nd century by the Greek prophet Alexander of Abonoteichos. Lucian was ill-disposed toward the cult, calling Alexander a false prophet and accusing the whole enterprise of being a hoax: Glycon himself was supposedly a hand puppet.

🔗 Cryptography 🔗 Cryptography/Computer science

In cryptography and steganography, plausibly deniable encryption describes encryption techniques where the existence of an encrypted file or message is deniable in the sense that an adversary cannot prove that the plaintext data exists.

The users may convincingly deny that a given piece of data is encrypted, or that they are able to decrypt a given piece of encrypted data, or that some specific encrypted data exists. Such denials may or may not be genuine. For example, it may be impossible to prove that the data is encrypted without the cooperation of the users. If the data is encrypted, the users genuinely may not be able to decrypt it. Deniable encryption serves to undermine an attacker's confidence either that data is encrypted, or that the person in possession of it can decrypt it and provide the associated plaintext.

In their pivotal 1996 paper, Ran Canetti, Cynthia Dwork, Moni Naor, and Rafail Ostrovsky introduced the concept of deniable encryption, a cryptographic breakthrough that ensures privacy even under coercion. This concept allows encrypted communication participants to plausibly deny the true content of their messages. Their work lays the foundational principles of deniable encryption, illustrating its critical role in protecting privacy against forced disclosures. This research has become a cornerstone for future advancements in cryptography, emphasizing the importance of deniable encryption in maintaining communication security. The notion of deniable encryption was used by Julian Assange and Ralf Weinmann in the Rubberhose filesystem.