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The Great Stirrup Controversy is the academic debate about the Stirrup Thesis, the theory that feudalism in Europe developed largely as a result of the introduction of the stirrup to cavalry in the 8th century CE. It relates to the hypothesis suggested by Lynn Townsend White Jr. in his 1962 book, Medieval Technology and Social Change. White believed that the stirrup enabled heavy cavalry and shock combat, which in turn prompted the Carolingian dynasty of the 8th and 9th centuries to organize its territory into a vassalage system, rewarding mounted warriors with land grants for their service. White's book has proved very influential, but others have accused him of speculation, oversimplification, and ignoring contradictory evidence on the subject. Scholars have debated whether the stirrup actually provided the impetus for this social change, or whether the rise of heavy cavalry resulted from political changes in Medieval Europe.

The man or boy test was proposed by computer scientist Donald Knuth as a means of evaluating implementations of the ALGOL 60 programming language. The aim of the test was to distinguish compilers that correctly implemented "recursion and non-local references" from those that did not.

There are quite a few ALGOL60 translators in existence which have been designed to handle recursion and non-local references properly, and I thought perhaps a little test-program may be of value. Hence I have written the following simple routine, which may separate the man-compilers from the boy-compilers.

"The quick brown fox jumps over the lazy dog" is an English-language pangram—a sentence that contains all of the letters of the alphabet. It is commonly used for touch-typing practice, testing typewriters and computer keyboards, displaying examples of fonts, and other applications involving text where the use of all letters in the alphabet is desired. Owing to its brevity and coherence, it has become widely known.

The Pax calendar was invented by James A. Colligan, SJ in 1930 as a perennializing reform of the annualized Gregorian calendar.

Utility fog (coined by Dr. John Storrs Hall in 1989) is a hypothetical collection of tiny robots that can replicate a physical structure. As such, it is a form of self-reconfiguring modular robotics.

In computer science, corecursion is a type of operation that is dual to recursion. Whereas recursion works analytically, starting on data further from a base case and breaking it down into smaller data and repeating until one reaches a base case, corecursion works synthetically, starting from a base case and building it up, iteratively producing data further removed from a base case. Put simply, corecursive algorithms use the data that they themselves produce, bit by bit, as they become available, and needed, to produce further bits of data. A similar but distinct concept is generative recursion which may lack a definite "direction" inherent in corecursion and recursion.

Where recursion allows programs to operate on arbitrarily complex data, so long as they can be reduced to simple data (base cases), corecursion allows programs to produce arbitrarily complex and potentially infinite data structures, such as streams, so long as it can be produced from simple data (base cases) in a sequence of finite steps. Where recursion may not terminate, never reaching a base state, corecursion starts from a base state, and thus produces subsequent steps deterministically, though it may proceed indefinitely (and thus not terminate under strict evaluation), or it may consume more than it produces and thus become non-productive. Many functions that are traditionally analyzed as recursive can alternatively, and arguably more naturally, be interpreted as corecursive functions that are terminated at a given stage, for example recurrence relations such as the factorial.

Corecursion can produce both finite and infinite data structures as results, and may employ self-referential data structures. Corecursion is often used in conjunction with lazy evaluation, to produce only a finite subset of a potentially infinite structure (rather than trying to produce an entire infinite structure at once). Corecursion is a particularly important concept in functional programming, where corecursion and codata allow total languages to work with infinite data structures.

"Hebban olla vogala", sometimes spelled "hebban olla uogala", are the first three words of an 11th-century text fragment written in Old Dutch. The fragment was discovered in 1932 on the flyleaf of a manuscript that was probably made in the abbey of Rochester, Kent and is kept in Oxford. It is usually considered to represent a West Flemish variant of Old Low Franconian.

An often cited poem, it was long believed by many Dutch people to be the only text remaining of Old Dutch. However, experts were already aware of other sources that were then not yet easily accessible. Today, more than 42,000 Old Dutch words and phrases from sources such as the Wachtendonck Psalms and the Leiden Willeram have been discovered, with the oldest definitive source being the Salian Law.

Frederick Travis Dibnah, (29 April 1938 – 6 November 2004) was an English steeplejack and television personality, with a keen interest in mechanical engineering, who described himself as a "backstreet mechanic".

When Dibnah was born, Britain relied heavily upon coal to fuel its industry. As a child, he was fascinated by the steam engines which powered the many textile mills in Bolton, but he paid particular attention to chimneys and the men who worked on them. He began his working life as a joiner, before becoming a steeplejack. From age 22, he served for two years in the Army Catering Corps of the British Army, undertaking his National Service. Once demobilised, he returned to steeplejacking but met with limited success until he was asked to repair Bolton's parish church. The resulting publicity provided a boost to his business, ensuring he was almost never out of work.

In 1978, while making repairs to Bolton Town Hall, Dibnah was filmed by a regional BBC news crew. The BBC then commissioned a documentary, which followed the rough-hewn steeplejack as he worked on chimneys, interacted with his family and talked about his favourite hobby—steam. His Lanky manner and gentle, self-taught philosophical outlook proved popular with viewers and he featured in a number of television programmes. Toward the end of his life, the decline of Britain's industry was mirrored by a decline in his steeplejacking business and Dibnah increasingly came to rely on public appearances and after-dinner speaking to support his income. In 1998, he presented a programme on Britain's industrial history and went on to present a number of series, largely concerned with the Industrial Revolution and its mechanical and architectural legacy.

He died from bladder cancer in November 2004, aged 66.

The elephant clock was a medieval invention by Al-Jazari (1136–1206), an Arab engineer and inventor of various clocks. The device consisted of a weight powered water clock in the form of an Asian elephant. This horological technology was derived from earlier Indian clocks and Chinese clocks.

In China clock escapement mechanism was invented by the polymath and Buddhist monk Yi Xing as well as the hydraulic powered waterwheel and water clock in the mechanically-driven and rotated equatorial armillary sphere of the polymaths Zhang Heng and Ma Jun. The Elephant clock had some design differences compared to earlier Indian and Chinese clocks and the various elements of the clock are in the housing (howdah) on top of the elephant.

Al-Jazari upon finishing the development and construction of his Elephant clock wrote: "The elephant represents the Indian and African cultures, the two dragons represents Chinese culture, the phoenix represents Persian culture, the water work represents Greek culture, and the turban represents Islamic culture" signifying the multicultural mentality of the intellectual Al-Jazari.

In addition to its mechanical innovations, the clock itself is seen as an early example of multiculturalism represented in technology.