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🔗 Mathematics 🔗 Economics 🔗 Politics 🔗 Game theory

In game theory, the Nash equilibrium, named after the mathematician John Forbes Nash Jr., is a proposed solution of a non-cooperative game involving two or more players in which each player is assumed to know the equilibrium strategies of the other players, and no player has anything to gain by changing only their own strategy.

In terms of game theory, if each player has chosen a strategy, and no player can benefit by changing strategies while the other players keep theirs unchanged, then the current set of strategy choices and their corresponding payoffs constitutes a Nash equilibrium.

Stated simply, Alice and Bob are in Nash equilibrium if Alice is making the best decision she can, taking into account Bob's decision while his decision remains unchanged, and Bob is making the best decision he can, taking into account Alice's decision while her decision remains unchanged. Likewise, a group of players are in Nash equilibrium if each one is making the best decision possible, taking into account the decisions of the others in the game as long as the other parties' decisions remain unchanged.

Nash showed that there is a Nash equilibrium for every finite game: see further the article on strategy.

🔗 China 🔗 Novels 🔗 Novels/Science fiction 🔗 Science Fiction

The Dark Forest (Chinese: 黑暗森林) is a 2008 science fiction novel by the Chinese writer Liu Cixin. It is the sequel to the Hugo Award-winning novel The Three-Body Problem in the trilogy titled Remembrance of Earth's Past, but Chinese readers generally refer to the series by the title of the first novel. The English version, translated by Joel Martinsen, was published in 2015. The novel is about the dark forest hypothesis (which was named after the novel), a possible solution to the Fermi paradox, though similar theories have been described as early as 1983.

🔗 Computing

ECMAScript for XML (E4X) is the standard ISO/IEC 22537:2006 [1] programming language extension that adds native XML support to ECMAScript (which includes ActionScript, JavaScript, and JScript). The goal is to provide an alternative to DOM interfaces that uses a simpler syntax for accessing XML documents. It also offers a new way of making XML visible. Before the release of E4X, XML was always accessed at an object level. E4X instead treats XML as a primitive (like characters, integers, and booleans). This implies faster access, better support, and acceptance as a building block (data structure) of a program.

E4X is standardized by Ecma International in the ECMA-357 standard. The first edition was published in June 2004, the second edition in December 2005.

The E4X standard was deprecated by the Mozilla Foundation in 2014.

🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Asian military history 🔗 Military history/Southeast Asian military history 🔗 Vietnam

Operation Popeye (Project Controlled Weather Popeye / Motorpool / Intermediary-Compatriot) was a highly classified weather modification program in Southeast Asia during 1967–1972. The cloud seeding operation during the Vietnam War ran from March 20, 1967 until July 5, 1972 in an attempt to extend the monsoon season, specifically over areas of the Ho Chi Minh Trail. The operation was used to induce rain and extend the East Asian Monsoon season in support of U.S. government efforts related to the War in Southeast Asia.

The former U.S. Secretary of Defense, Robert S. McNamara, was aware that there might be objections raised by the international scientific community but said in a memo to the president that such objections had not in the past been a basis for prevention of military activities considered to be in the interests of U.S. national security.

The chemical weather modification program was conducted from Thailand over Cambodia, Laos, and Vietnam and allegedly sponsored by Secretary of State Henry Kissinger and CIA without the authorization of then Secretary of Defense Melvin Laird who had categorically denied to Congress that a program for modification of the weather for use as a tactical weapon even existed.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Military history/Medieval warfare

A rondel dagger or roundel dagger was a type of stiff-bladed dagger in Europe in the late Middle Ages (from the 14th century onwards), used by a variety of people from merchants to knights. It was worn at the waist and might be used as a utility tool, or worn into battle or in a jousting tournament as a side arm.

The rondel dagger featured a long, slim steel blade with a round or circular hand guard and pommel. Designed for close-quarter combat, it was effective in puncturing and bursting mail armor links and penetrating weak points in plate armor. The dagger evolved from the early knightly dagger and became the standard side-arm for knights in the 15th century. It was used as a backup weapon for hand-to-hand fighting and as a tool to force surrender, as captured knights could be ransomed. The rondel dagger also gained popularity among the middle class in the 15th century. Various combat techniques involving the rondel dagger can be found in Hans Talhoffer's combat manuals from the 1440s to 1460s.

🔗 Internet

Cicada 3301 is a nickname given to an organization that on three occasions has posted a set of puzzles to recruit codebreakers from the public. The first internet puzzle started on January 4, 2012 on 4chan and ran for approximately one month. A second round began one year later on January 4, 2013, and then a third round following the confirmation of a fresh clue posted on Twitter on January 4, 2014. The stated intent was to recruit "intelligent individuals" by presenting a series of puzzles which were to be solved. No new puzzles were published on January 4, 2015. However, a new clue was posted on Twitter on January 5, 2016. In April 2017 a verified PGP-signed message was found: Beware false paths. Always verify PGP signature from 7A35090F. That message explicitly denies the validity of any unsigned puzzle, as recently as April 2017.

The puzzles focused heavily on data security, cryptography, steganography, internet anonymity, and surveillance.

It has been called "the most elaborate and mysterious puzzle of the internet age" and is listed as one of the "top 5 eeriest, unsolved mysteries of the internet", and much speculation exists as to its function. Many have speculated that the puzzles are a recruitment tool for the NSA, CIA, MI6, a "Masonic conspiracy" or a cyber mercenary group. Others have claimed Cicada 3301 is an alternate reality game. No company or individual has taken credit for it or attempted to monetize it, however.

🔗 Human rights 🔗 Russia 🔗 Death 🔗 Iran 🔗 Discrimination 🔗 Turkey 🔗 Ethnic groups 🔗 Russia/politics and law of Russia 🔗 Russia/history of Russia 🔗 Caucasia 🔗 Crime and Criminal Biography 🔗 Abkhazia

The Circassian genocide, or Tsitsekun, was the systematic mass killing, ethnic cleansing, and forced displacement of between 95% and 97% of the Circassian people during the final stages of the Russian invasion of Circassia in the 19th century. It resulted in the deaths of between 1,000,000 and 1.5 million and the destruction of Circassia, which was then annexed by the Russian Empire. Those planned for extermination were mainly the Circassians, who are predominantly Muslims, but other ethnic groups in the Caucasus were also affected, as part of the Caucasian War. The Imperial Russian Army also impaled their victims and tore open the bellies of pregnant women to intimidate the Circassians and devastate their morale. Many Russian generals, such as Grigory Zass, described the Circassians as a "lowly race" to justify and glorify their wholesale slaughter and their use as human test subjects in unethical scientific experiments. Russian soldiers were also permitted to rape Circassian women.

The native Circassian population was largely decimated or expelled to the Ottoman Empire. Only those who accepted Russification and made agreements with Russian troops, were spared. Starvation was used as a tool of war against Circassian villages, many of which were subsequently burned down. Russian writer Leo Tolstoy reported that Russian soldiers attacked village houses at night. British diplomat Gifford Palgrave, stated that "their only crime was not being Russian." Seeking military intervention against Russia, Circassian officials sent "A Petition from Circassian leaders to Her Majesty Queen Victoria" in 1864, but were unsuccessful in their attempt to solicit aid from the British Empire. That same year, the Imperial Russian Army launched a campaign of mass deportation of Circassia's surviving population. By 1867, a large portion of the Circassians were expelled. Many died from epidemics or starvation. Some were reportedly eaten by dogs after their death, while others died when their ships sank during storms of black sea.

Most sources state that as little as 3% of Circassia's population remained after the genocide and that as many as 1.5 million people were forced to flee in total, though only around half of them survived the journey. Ottoman archives show the intake of more than a million immigrants from the Caucasus by 1879, with nearly half of them having been found dying on the shores of the Black Sea as a result of disease. Presuming that these statistics are accurate, Russia's military campaign in Circassia constitutes the single largest genocide of the 19th century. Russian records, in confirmation of the Ottoman archives, documented the presence of only 106,798 Circassians in the Caucasus on the approach to the 20th century. Other estimates by Russian historiographers are even lower, ranging from 40,400 to 65,900. The Russian Empire census, conducted in 1897, reported the presence of 150,000 Circassians in the conquered region.

Classified Russian Imperial archives in Georgia were opened to historians by the Georgian government, which revealed previously unknown information regarding Russian actions. Following this, on May 20, 2011, Georgia formally recognized the Circassian genocide. Ukraine recognized the Circassian genocide on 9 January 2025, following Circassian appeals in June 2024. The city of Wayne, New Jersey in the United States and the East Turkistan Exile Government have also officially recognized the Circassian genocide. On February 7, 1992, the Kabardino-Balkarian Autonomous Soviet Socialist Republic decided to condemn the Circassian Genocide. On May 12, 1994, the Republic of Kabardino-Balkaria and on April 29, 1996, the Republic of Adygea submitted applications to the State Duma of the Russian Federation for the recognition of the Circassian Genocide. In October 2006, 20+ Circassian associations appealed to the European Parliament to recognize the Circassian Genocide. In November 2006, Circassian associations in the Republics of Adygea, Kabardino-Balkaria and Karachay-Cherkessia appealed to Russian president Vladimir Putin to recognize the Circassian Genocide. The Russian Federation classifies the events in Circassia as a mass migration (Russian: Черкесское мухаджирство, lit. 'Circassian migrationism') and denies that a genocide took place. 21 May is observed annually as the Circassian Day of Mourning, which consists of ceremonies and marches in memory of the victims and, sometimes, protests against the Russian government. Today, the Circassian diaspora is primarily concentrated in Turkey and Jordan, with some 750,000 living in Russia's North Caucasus Economic Region.

🔗 Skepticism 🔗 Paranormal 🔗 Cryptozoology

The following is a list of unidentified, or formerly unidentified, sounds. All of the sound files in this article have been sped up by at least a factor of 16 to increase intelligibility by condensing them and raising the frequency from infrasound to a more audible and reproducible range.

🔗 Trains 🔗 Trains/Monorail

The Wuppertaler Schwebebahn (Wuppertal Suspension Railway) is a suspension railway in Wuppertal, Germany.

Its full name is Anlage einer elektrischen Hochbahn (Schwebebahn), System Eugen Langen. ("Electric Elevated Railway (Suspension Railway) Installation, Eugen Langen System") It is the oldest electric elevated railway with hanging cars in the world and is a unique system.

Designed by Eugen Langen to sell to the city of Berlin, the installation with elevated stations was built in Barmen, Elberfeld and Vohwinkel between 1897 and 1903; the first track opened in 1901. The Schwebebahn is still in use today as a normal means of local public transport, moving 25 million passengers annually (2008).

The Schwebebahn runs along a route of 13.3 kilometres (8.3 mi), at a height of about 12 metres (39 ft) above the River Wupper between Oberbarmen and Sonnborner Straße (10 kilometres or 6.2 miles) and about 8 metres (26 ft) above the valley road between Sonnborner Straße and Vohwinkel (3.3 kilometres or 2.1 miles). At one point the railway crosses the A46 motorway. The entire trip takes about 30 minutes. The Schwebebahn operates within the VRR transport association and accepts tickets issued by the VRR companies.

Due to an accident in November 2018, the Schwebebahn was closed down for nearly nine months. It re-opened on 1 August 2019.