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🔗 Computing 🔗 Computer science 🔗 Computing/Software

A Turing tarpit (or Turing tar-pit) is any programming language or computer interface that allows for flexibility in function but is difficult to learn and use because it offers little or no support for common tasks. The phrase was coined in 1982 by Alan Perlis in the Epigrams on Programming:

54. Beware of the Turing tar-pit in which everything is possible but nothing of interest is easy.

In any Turing complete language, it is possible to write any computer program, so in a very rigorous sense nearly all programming languages are equally capable. Showing that theoretical ability is not the same as usefulness in practice, Turing tarpits are characterized by having a simple abstract machine that requires the user to deal with many details in the solution of a problem. At the extreme opposite are interfaces that can perform very complex tasks with little human intervention but become obsolete if requirements change slightly.

Some esoteric programming languages, such as Brainfuck, are specifically referred to as "Turing tarpits" because they deliberately implement the minimum functionality necessary to be classified as Turing complete languages. Using such languages is a form of mathematical recreation: programmers can work out how to achieve basic programming constructs in an extremely difficult but mathematically Turing-equivalent language.

🔗 Apple Inc./Macintosh 🔗 Apple Inc. 🔗 Apple Inc./Mac

The Command key (sometimes abbreviated as Cmd key), ⌘, formerly also known as the Apple key or open Apple key, is a modifier key present on Apple keyboards. The Command key's purpose is to allow the user to enter keyboard commands in applications and in the system. An "extended" Macintosh keyboard—the most common type—has two command keys, one on each side of the space bar; some compact keyboards have one only on the left.

The ⌘ symbol (the "looped square") was chosen by Susan Kare after Steve Jobs decided that the use of the Apple logo in the menu system (where the keyboard shortcuts are displayed) would be an over-use of the logo. Apple's adaptation of the symbol—encoded in Unicode at U+2318—was derived in part from its use in Nordic countries as an indicator of cultural locations and places of interest. The symbol is known by various other names, including "Saint John's Arms" and "Bowen knot".

🔗 Military history 🔗 Military history/Medieval warfare 🔗 Martial arts 🔗 Military history/Spanish military history 🔗 Spain 🔗 Military history/European military history 🔗 Fencing

La Verdadera Destreza is the conventional term for the Spanish tradition of fencing of the early modern period. The word destreza literally translates to 'dexterity' or 'skill, ability', and thus la verdadera destreza to 'the true skill' or 'the true art'.

While destreza is primarily a system of swordsmanship, it is intended to be a universal method of fighting, applicable to all weapons in principle, but in practice dedicated to the rapier specifically, or the rapier combined with a defensive weapon such as a cloak, a buckler or a parrying dagger, besides other weapons such as the late-renaissance two-handed montante; the flail; and polearms such as the pike and halberd.

Its precepts are based on reason, geometry, and tied to intellectual, philosophical, and moral ideals, incorporating various aspects of a well-rounded Renaissance humanist education, with a special focus on the writings of classical authors such as Aristotle, Euclid, and Plato.

The tradition is documented in scores of fencing manuals, but centers on the works of two primary authors, Jerónimo Sánchez de Carranza (Hieronimo de Carança, died c. 1608) and his student Luis Pacheco de Narváez (1570–1640).

🔗 Television

TV detector vans are vans, which, according to the BBC, contain equipment that can detect the presence of television sets in use. The vans are operated by contractors working for the BBC, to enforce the television licensing system in the UK, the Channel Islands and on the Isle of Man. The veracity of their operation has been called into question in the media.

🔗 Astronomy 🔗 Astronomy/Solar System

The Galilean moons (), or Galilean satellites, are the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto. They are the most readily visible Solar System objects after Saturn, the dimmest of the classical planets; though their closeness to bright Jupiter makes naked-eye observation very difficult, they are readily seen with common binoculars, even under night sky conditions of high light pollution. The invention of the telescope enabled the discovery of the moons in 1610. Through this, they became the first Solar System objects discovered since humans have started tracking the classical planets, and the first objects to be found to orbit any planet beyond Earth.

They are planetary-mass moons and among the largest objects in the Solar System. All four, along with Titan, Triton, and Earth's Moon, are larger than any of the Solar System's dwarf planets. The largest, Ganymede, is the largest moon in the Solar System and surpasses the planet Mercury in size (though not mass). Callisto is only slightly smaller than Mercury in size; the smaller ones, Io and Europa, are about the size of the Moon. The three inner moons — Io, Europa, and Ganymede — are in a 4:2:1 orbital resonance with each other. While the Galilean moons are spherical, all of Jupiter's remaining moons have irregular forms because they are too small for their self-gravitation to pull them into spheres.

The Galilean moons are named after Galileo Galilei, who observed them in either December 1609 or January 1610, and recognized them as satellites of Jupiter in March 1610; they remained the only known moons of Jupiter until the discovery of the fifth largest moon of Jupiter Amalthea in 1892. Galileo initially named his discovery the Cosmica Sidera ("Cosimo's stars") or Medicean Stars, but the names that eventually prevailed were chosen by Simon Marius. Marius discovered the moons independently at nearly the same time as Galileo, 8 January 1610, and gave them their present individual names, after mythological characters that Zeus seduced or abducted, which were suggested by Johannes Kepler in his Mundus Jovialis, published in 1614. Their discovery showed the importance of the telescope as a tool for astronomers by proving that there were objects in space that cannot be seen by the naked eye. The discovery of celestial bodies orbiting something other than Earth dealt a serious blow to the then-accepted (among educated Europeans) Ptolemaic world system, a geocentric theory in which everything orbits around Earth.

🔗 Food and drink 🔗 Birds

A chicken can be hypnotized, or put into a trance, by holding its head down against the ground, and drawing a line along the ground with a stick or a finger, starting at the beak and extending straight outward in front of the chicken. If the chicken is hypnotized in this manner, it will continue to stare at the line, remaining immobile for as long as 30 minutes. Other methods of inducing this state are also known. Ethologists refer to this state as 'tonic immobility' i.e. a natural state of semi-paralysis that some animals enter when presented with a threat, which is probably a defensive mechanism intended to feign death, albeit rather poorly.

The first known written reference for this method came in 1646, in Mirabele Experimentum de Imaginatione Gallinae by Athanasius Kircher in Rome.

🔗 Comics

"Cow tools" is a cartoon from The Far Side by American cartoonist Gary Larson, published in October 1982. It depicts a cow standing behind a table of bizarre, misshapen implements with the caption "cow tools". The cartoon confused many readers, who wrote or phoned in seeking an explanation of the joke. In response to the controversy, Larson issued a press release clarifying that the thrust of the cartoon was simply that, if a cow were to make tools, they would "lack something in sophistication". It has been described as "arguably the most loathed Far Side strip ever" while also becoming a popular internet meme.

A hydraulic telegraph (Greek: υδραυλικός τηλέγραφος) is either of two different hydraulic-telegraph telecommunication systems. The earliest one was developed in 4th-century BC Greece, while the other was developed in 19th-century AD Britain. The Greek system was deployed in combination with semaphoric fires, while the latter British system was operated purely by hydraulic fluid pressure.

Although both systems employed water in their sending and receiver devices, their transmission media were completely different. The ancient Greek system transmitted its semaphoric information to the receiver visually, which limited its use to line-of-sight distances in good visibility weather conditions only. The 19th-century British system used water-filled pipes to effect changes to the water level in the receiver unit (similar to a transparent water-filled flexible tube used as a level indicator), thus limiting its range to the hydraulic pressure that could be generated at the transmitter's device.

While the Greek device was extremely limited in the codes (and hence the information) it could convey, the British device was never deployed in operation other than for very short-distance demonstrations. Although the British device could be used in any visibility within its range of operation, it could not work in sub-zero temperatures without additional infrastructure to heat the pipes. This contributed to its impracticality.

🔗 Music theory 🔗 Classical music 🔗 Music/Music genres

Aleatoric music (also aleatory music or chance music; from the Latin word alea, meaning "dice") is music in which some element of the composition is left to chance, and/or some primary element of a composed work's realization is left to the determination of its performer(s). The term is most often associated with procedures in which the chance element involves a relatively limited number of possibilities.

The term became known to European composers through lectures by acoustician Werner Meyer-Eppler at the Darmstadt International Summer Courses for New Music in the beginning of the 1950s. According to his definition, "a process is said to be aleatoric ... if its course is determined in general but depends on chance in detail". Through a confusion of Meyer-Eppler's German terms Aleatorik (noun) and aleatorisch (adjective), his translator created a new English word, "aleatoric" (rather than using the existing English adjective "aleatory"), which quickly became fashionable and has persisted. More recently, the variant "aleatoriality" has been introduced.