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The Weber–Fechner law refers to two related hypotheses in the field of psychophysics, known as Weber's law and Fechner's law. Both laws relate to human perception, more specifically the relation between the actual change in a physical stimulus and the perceived change. This includes stimuli to all senses: vision, hearing, taste, touch, and smell.

The Breitspurbahn (German pronunciation: [ˈbʁaɪtʃpuːɐ̯baːn], transl. broad-gauge railway) was a railway system planned and partly surveyed by Nazi Germany. Its track gauge – the distance between the two running rails – was to be 3000 mm (9 ft 10+1⁄8 in), more than twice that of the 1435 mm (4 ft 8+1⁄2 in) standard gauge used in western Europe. The railway was intended initially to run between major cities of the Greater Germanic Reich (the regime's expanded Germany) and neighbouring states.

The world's most livable cities is an informal name given to any list of cities as they rank on an annual survey of living conditions. In addition to providing clean water, clean air, adequate food and shelter, a ‘livable’ city must also generate a sense of community and offer hospitable settings for all, especially young people, to develop social skills, a sense of autonomy and identity.

Regions with cities commonly ranked in the top 50 include Australia, New Zealand, Canada and Europe. Three examples of such surveys are Monocle's "Most Liveable Cities Index", the Economist Intelligence Unit's "Global Liveability Ranking", and "Mercer Quality of Living Survey". Numbeo has the largest statistics and survey data based on cities and countries. Deutsche Bank's Liveability Survey is another ranking of cities by quality of life.

In data mining and statistics, hierarchical clustering (also called hierarchical cluster analysis or HCA) is a method of cluster analysis that seeks to build a hierarchy of clusters. Strategies for hierarchical clustering generally fall into two categories:

• Agglomerative: This is a "bottom-up" approach: Each observation starts in its own cluster, and pairs of clusters are merged as one moves up the hierarchy.
• Divisive: This is a "top-down" approach: All observations start in one cluster, and splits are performed recursively as one moves down the hierarchy.

In general, the merges and splits are determined in a greedy manner. The results of hierarchical clustering are usually presented in a dendrogram.

Hierarchical clustering has the distinct advantage that any valid measure of distance can be used. In fact, the observations themselves are not required: all that is used is a matrix of distances. On the other hand, except for the special case of single-linkage distance, none of the algorithms (except exhaustive search in ${\displaystyle {\mathcal {O}}(2^{n})}$) can be guaranteed to find the optimum solution.

Go! is an agent-based programming language in the tradition of logic-based programming languages like Prolog. It was introduced in a 2003 paper by Francis McCabe and Keith Clark.

The naming law in Sweden (Swedish: lag om personnamn) is a Swedish law which requires approval of the government agency for names to be given to Swedish children. The parents must submit the proposed name of a child within three months of birth. The current law was enacted in 2017, replacing a 1982 law. The Swedish Tax Agency administers the registration of names in Sweden. The law has been revised since originally enacted; in 1983, it was made possible for men to adopt their wife's or partner's name, as well as for women to adopt their husband's name.

The 1982 law states, in part: "First names shall not be approved if they can cause offense or can be supposed to cause discomfort for the one using it, or names which for some obvious reason are not suitable as a first name" (§ 34). This text applies both when parents name their children and when an adult wants to change their own name. When changing a name, the first change is free of charge as long as at least one of the names given at birth is kept, and such a change is only allowed once per person. Further name changes require fee payment. The law states nothing about registering which name is used on a daily basis, but the tax authority can register that if requested.

Letterlocking is the act of folding and securing a written message which could be on papyrus, parchment, or paper, so that it does not require an envelope or additional enclosure. It is a document security tradition which utilizes folding and cutting. The process dates to the 13th century in Western history, corresponding with the availability of flexible writing paper. Letterlocking uses small slits, tab, and holes placed directly into a letter, which combined with folding techniques are used to secure the letter ("letterpacket"), preventing reading the letter without breaking seals or slips, providing a means of tamper resistance. These folds and holes may be additionally secured with string and sealing wax. A Scottish diplomat in Italy, William Keith of Delny, sent letters to James VI of Scotland which would tear in two if not opened with care.

Intricate letterlocking works contain artistic elements, demonstrating more than a utilitarian purpose. While the use of sealing techniques may have been limited to ecclesiastic and the nobility, letterlocking was historically performed by all classes of writers. An individual could also be recognised by their personal technique of folding, as was the case with Jane Whorwood, of whose letter Charles I, imprisoned in Carisbrooke Castle on the Isle of Wight, wrote: "This Note [...] I know, by the fowldings [...] that it is written by [Mrs Whorwood]".

Letterlocking is also a discipline focusing on "the materially engineered security and privacy of letters, both as a technology and a historically evolving tradition."

On 11 March 2022, Mark Izraylevich Bernstein (Russian: Марк Израйлевич Бернштейн), a Belarusian blogger and editor of the Russian-language Wikipedia based in Minsk, was detained by the Belarusian GUBOPiK security force after online accusations of violating the 2022 Russian fake news law for his editing of Wikipedia articles on the topic of the 2022 Russian invasion of Ukraine. He was sentenced to 15 days' administrative arrest under Article 24.3 of the Administrative Code of Belarus (for disobedience to police officers).

Umarell (Italian pronunciation: [umaˈrɛl]; modern revisitation of the Bolognese dialect word umarèl [umaˈrɛːl]) is a term in the Italo-Romance variety of Bologna referring specifically to men of retirement age who spend their time watching construction sites, especially roadworks – stereotypically with hands clasped behind their back and offering unwanted advice. Its literal meaning is "little man" (also umarèin). The term is employed as lighthearted mockery or self-deprecation.

The modern term was popularised in 2005 by local writer Danilo Masotti through two books and an associated blog. In December 2020, the word was included in the Zingarelli dictionary.

The Peirce quincuncial projection is a conformal map projection developed by Charles Sanders Peirce in 1879. The projection has the distinctive property that it can be tiled ad infinitum on the plane, with edge-crossings being completely smooth except for four singular points per tile. The projection has seen use in digital photography for portraying 360° views. The description quincuncial refers to the arrangement of four quadrants of the globe around the center hemisphere in an overall square pattern. Typically the projection is oriented such that the north pole lies at the center.