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π Quiescence search
Quiescence search is an algorithm typically used to extend search at unstable nodes in minimax game trees in game-playing computer programs. It is an extension of the evaluation function to defer evaluation until the position is stable enough to be evaluated statically, that is, without considering the history of the position or future moves from the position. It mitigates the effect of the horizon problem faced by AI engines for various games like chess and Go.
Human players usually have enough intuition to decide whether to abandon a bad-looking move, or search a promising move to a great depth. A quiescence search attempts to emulate this behavior by instructing a computer to search "volatile" positions to a greater depth than "quiet" ones to make sure there are no hidden traps and to get a better estimate of its value.
Any sensible criterion may be used to distinguish "quiet" positions from "volatile" positions. One common criterion is that moves exist in the position that can dramatically change the valuation of the position, such as captures in chess or Go. As the main motive of quiescence search is to get a stable value out of a static evaluation function, it may also make sense to detect wide fluctuations in values returned by a simple heuristic evaluator over several ply, i.e. a history criterion. The quiescence search continues as along as the position remains volatile according to the criterion. In order to get the quiescence search to terminate, plies are usually restricted to moves that deal directly with the threat, such as moves that capture and recapture (often called a 'capture search') in chess. In highly "unstable" games like Go and reversi, a rather large proportion of computer time may be spent on quiescence searching.
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- "Quiescence search" | 2022-06-09 | 12 Upvotes 1 Comments
π Transactional analysis
Transactional analysis (TA) is a psychoanalytic theory and method of therapy wherein social transactions are analyzed to determine the ego state of the patient (whether parent-like, childlike, or adult-like) as a basis for understanding behavior. In transactional analysis, the patient is taught to alter the ego state as a way to solve emotional problems. The method deviates from Freudian psychoanalysis which focuses on increasing awareness of the contents of unconsciously held ideas. Eric Berne developed the concept and paradigm of transactional analysis in the late 1950s.
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- "Transactional analysis" | 2015-06-23 | 13 Upvotes 2 Comments
π Stonehenge Archer
The Stonehenge Archer is the name given to a Bronze Age man whose body was discovered in the outer ditch of Stonehenge. Unlike most burials in the Stonehenge Landscape, his body was not in a barrow, although it did appear to have been deliberately and carefully buried in the ditch.
Examination of the skeleton indicated that the man was local to the area and aged about 30 when he died. Radiocarbon dating suggests that he died around 2300 BCE, making his death roughly contemporary with the Amesbury Archer and the Boscombe Bowmen buried 3 miles away in Amesbury.
He came to be known as an archer because of the stone wrist-guard and a number of flint arrowheads buried with him. In fact, several of the arrowheads' tips were located in the skeleton's bones, suggesting that the man had been killed by them.
His body was excavated in 1978 by Richard Atkinson and John G. Evans who had been re-examining an older trench in the ditch and bank of Stonehenge. His remains are now housed in the Salisbury Museum in Salisbury.
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- "Stonehenge Archer" | 2024-07-01 | 30 Upvotes 13 Comments
π Value of life
The value of life is an economic value used to quantify the benefit of avoiding a fatality. It is also referred to as the cost of life, value of preventing a fatality (VPF), implied cost of averting a fatality (ICAF), and value of a statistical life (VSL). In social and political sciences, it is the marginal cost of death prevention in a certain class of circumstances. In many studies the value also includes the quality of life, the expected life time remaining, as well as the earning potential of a given person especially for an after-the-fact payment in a wrongful death claim lawsuit.
As such, it is a statistical term, the cost of reducing the average number of deaths by one. It is an important issue in a wide range of disciplines including economics, health care, adoption, political economy, insurance, worker safety, environmental impact assessment, globalization, and process safety.
The motivation for placing a monetary value on life is to enable policy and regulatory analysts to allocate the limited supply of resources, infrastructure, labor, and tax revenue. Estimates for the value of a life are used to compare the life-saving and risk-reduction benefits of new policies, regulations, and projects against a variety of other factors, often using a cost-benefit analysis.
Estimates for the statistical value of life are published and used in practice by various government agencies. In Western countries and other liberal democracies, estimates for the value of a statistical life typically range from US$1 millionβUS$10 million; for example, the United States FEMA estimated the value of a statistical life at US$7.5 million in 2020.
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- "Value of life" | 2024-01-08 | 74 Upvotes 92 Comments
π Nyctography: A substituton cypher by Lewis Carroll
Nyctography (in Nyctography: ) is a form of substitution cipher writing created by Lewis Carroll (Charles Lutwidge Dodgson) in 1891. It is written with a nyctograph (a device invented by Carroll) and uses a system of dots and strokes all based on a dot placed in the upper left corner. Using the Nyctograph, one could quickly jot down ideas or notes without the aid of light. Carroll invented the Nyctograph and Nyctography as he was often awakened during the night with thoughts that needed to be written down at once, and didn't want to go through the lengthy process of lighting a lamp only to have to then extinguish it.
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- "Nyctography: A substituton cypher by Lewis Carroll" | 2026-07-28 | 82 Upvotes 15 Comments
π Wardenclyffe Tower a.k.a. the Tesla Tower
Wardenclyffe Tower (1901β1917), also known as the Tesla Tower, was an early experimental wireless transmission station designed and built by Nikola Tesla in Shoreham, New York in 1901β1902. Tesla intended to transmit messages, telephony and even facsimile images across the Atlantic to England and to ships at sea based on his theories of using the Earth to conduct the signals. His decision to scale up the facility and add his ideas of wireless power transmission to better compete with Guglielmo Marconi's radio based telegraph system was met with refusal to fund the changes by the project's primary backer, financier J. P. Morgan. Additional investment could not be found, and the project was abandoned in 1906, never to become operational.
In an attempt to satisfy Tesla's debts, the tower was demolished for scrap in 1917 and the property taken in foreclosure in 1922. For 50 years, Wardenclyffe was a processing facility producing photography supplies. Many buildings were added to the site and the land it occupies has been trimmed down to 16 acres (6.5Β ha) but the original, 94 by 94Β ft (29 by 29Β m), brick building designed by Stanford White remains standing to this day.
In the 1980s and 2000s, hazardous waste from the photographic era was cleaned up, and the site was sold and cleared for new development. A grassroots campaign to save the site succeeded in purchasing the property in 2013, with plans to build a future museum dedicated to Nikola Tesla. In 2018 the property was listed on the National Register of Historic Places.
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- "Wardenclyffe Tower a.k.a. the Tesla Tower" | 2011-01-28 | 10 Upvotes 1 Comments
π Depopulation of cockroaches in post-Soviet states
Depopulation of cockroaches in post-Soviet states refers to observations that there has been a rapid disappearance of various types of cockroaches since the beginning of the 21st century in Russia and other countries of the former USSR. Various factors have been suggested as causes of the depopulation.
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- "Depopulation of cockroaches in post-Soviet states" | 2021-07-14 | 11 Upvotes 2 Comments
π Today: International Day to End Violence Against Sex Workers
International Day to End Violence Against Sex Workers is observed annually on December 17 by sex workers, their advocates, friends, families and allies. Originally conceived as a memorial and vigil for the victims of the Green River Killer in Seattle Washington, United States (US), it has evolved into an annual international event. The day calls attention to hate crimes committed against sex workers worldwide, as well as the need to remove the social stigma and discrimination that have contributed to violence against sex workers and indifference from the communities they are part of. Sex worker activists also state that custom and prohibitionist laws perpetuate such violence.
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- "Today: International Day to End Violence Against Sex Workers" | 2020-12-17 | 16 Upvotes 1 Comments
π Ytterby
Ytterby (Swedish pronunciation: [ΛΚΜtΛΙrΛbyΛ]) is a village on the Swedish island of ResarΓΆ, in Vaxholm Municipality in the Stockholm archipelago. Today the residential area is dominated by suburban homes.
The Swedish name of the village translates literally into "outer village". Ytterby is the single richest source of elemental discoveries in the world; the chemical elements yttrium (Y), terbium (Tb), erbium (Er), and ytterbium (Yb) are all named after Ytterby, and the elements holmium (Ho), scandium (Sc), thulium (Tm), tantalum (Ta), and gadolinium (Gd) were also first discovered there.
Local roads connect Ytterby to county road 274 and hence the mainland. Except for the winter months, passenger ships of the Waxholmsbolaget call at a pier in Ytterby, providing a connection to Vaxholm town and Stockholm. Ytterby is as well served by several local bus lines of the north east SL district, connecting the area directly to Stockholms Γstra station.
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- "Ytterby" | 2025-10-03 | 32 Upvotes 3 Comments
π Oil drilling: Wrong coordinate system creates lake 1,300 feet deep (1980)
Lake Peigneur (locally pronounced [pΓ¦ΜjΜΓ¦ΜΉΙΎ]) is a brackish lake in the U.S. state of Louisiana, 1.2 miles (1.9 kilometers) north of Delcambre and 9.1Β mi (14.6Β km) west of New Iberia, near the northernmost tip of Vermilion Bay. With a maximum depth of 200 feet (60 meters), it is the deepest lake in Louisiana.
It was a 10-foot-deep (3Β m) freshwater body, popular with sportsmen, until an unusual man-made disaster on November 20, 1980 changed its structure and the surrounding land.
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- "Oil drilling: Wrong coordinate system creates lake 1,300 feet deep (1980)" | 2018-11-30 | 32 Upvotes 3 Comments