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🔗 Mathematics 🔗 Statistics

Local regression or local polynomial regression, also known as moving regression, is a generalization of the moving average and polynomial regression. Its most common methods, initially developed for scatterplot smoothing, are LOESS (locally estimated scatterplot smoothing) and LOWESS (locally weighted scatterplot smoothing), both pronounced . They are two strongly related non-parametric regression methods that combine multiple regression models in a k-nearest-neighbor-based meta-model. In some fields, LOESS is known and commonly referred to as Savitzky–Golay filter (proposed 15 years before LOESS).

LOESS and LOWESS thus build on "classical" methods, such as linear and nonlinear least squares regression. They address situations in which the classical procedures do not perform well or cannot be effectively applied without undue labor. LOESS combines much of the simplicity of linear least squares regression with the flexibility of nonlinear regression. It does this by fitting simple models to localized subsets of the data to build up a function that describes the deterministic part of the variation in the data, point by point. In fact, one of the chief attractions of this method is that the data analyst is not required to specify a global function of any form to fit a model to the data, only to fit segments of the data.

The trade-off for these features is increased computation. Because it is so computationally intensive, LOESS would have been practically impossible to use in the era when least squares regression was being developed. Most other modern methods for process modeling are similar to LOESS in this respect. These methods have been consciously designed to use our current computational ability to the fullest possible advantage to achieve goals not easily achieved by traditional approaches.

A smooth curve through a set of data points obtained with this statistical technique is called a loess curve, particularly when each smoothed value is given by a weighted quadratic least squares regression over the span of values of the y-axis scattergram criterion variable. When each smoothed value is given by a weighted linear least squares regression over the span, this is known as a lowess curve; however, some authorities treat lowess and loess as synonyms.

🔗 Physics 🔗 Weather 🔗 Weather/Weather 🔗 Weather/General meteorology

A Fata Morgana (Italian: [ˈfaːta morˈɡaːna]) is a complex form of superior mirage visible in a narrow band right above the horizon. The term Fata Morgana is the Italian translation of "Morgan the Fairy" (Morgan le Fay of Arthurian legend). These mirages are often seen in the Italian Strait of Messina, and were described as fairy castles in the air or false land conjured by her magic.

Fata Morgana mirages significantly distort the object or objects on which they are based, often such that the object is completely unrecognizable. A Fata Morgana may be seen on land or at sea, in polar regions, or in deserts. It may involve almost any kind of distant object, including boats, islands, and the coastline. Often, a Fata Morgana changes rapidly. The mirage comprises several inverted (upside down) and upright images stacked on top of one another. Fata Morgana mirages also show alternating compressed and stretched zones.

The optical phenomenon occurs because rays of light bend when they pass through air layers of different temperatures in a steep thermal inversion where an atmospheric duct has formed. In calm weather, a layer of significantly warmer air may rest over colder dense air, forming an atmospheric duct that acts like a refracting lens, producing a series of both inverted and erect images. A Fata Morgana requires a duct to be present; thermal inversion alone is not enough to produce this kind of mirage. While a thermal inversion often takes place without there being an atmospheric duct, an atmospheric duct cannot exist without there first being a thermal inversion.

🔗 Mathematics

The Erdős number (Hungarian: [ˈɛrdøːʃ]) describes the "collaborative distance" between mathematician Paul Erdős and another person, as measured by authorship of mathematical papers. The same principle has been applied in other fields where a particular individual has collaborated with a large and broad number of peers.

🔗 Russia 🔗 Norway 🔗 Holidays 🔗 Sweden 🔗 Ethnic groups 🔗 Finland 🔗 Norse history and culture

The Sámi National Day is an ethnic national day for the Sámi (Saami) people that falls on February 6, the date when the first Sámi congress was held in 1917 in Trondheim, Norway. The congress was the first time that Norwegian and Swedish Sámi came together across national borders to work on finding solutions to common problems.

In 1992 at the 15th Sámi Conference in Helsinki, Finland, a resolution was passed that Sámi National Day should be celebrated on February 6 to commemorate the first Sámi congress in 1917, that Sami National Day is for all Sámi, regardless of where they live, and on that day the Sámi flag should be flown and the Sámi anthem sung in the local Sámi language. The first time Sami National Day was celebrated was in 1993, when the International Year of Indigenous People was proclaimed open in Jokkmokk, Sweden by the United Nations.

Since then, celebrating the day has become increasingly popular. In Norway, it is compulsory for municipal administrative buildings to fly the Norwegian flag, and optionally also the Sami flag, on February 6. Particularly notable is the celebration in Norway's capital Oslo, where the bells in the highest tower of Oslo City Hall play the Sami national anthem as the flags are raised. Some larger places have taken to arranging festivities in the week around the Sami National Day. The National Day has been included in the almanacs published by the University of Helsinki since 2004. The Norwegian, Swedish, and Finnish authorities recommend general flagging on the day.

By coincidence, February 6 was also the date representatives of the Sámi of the Kola Peninsula gathered annually to meet with Russian bureaucrats to debate and decide on issues of relevance to them. This assembly, called the Kola Sobbar, has been dubbed the "first Sámi Parliament" by the researcher Johan Albert Kalstad. However, the founding of the Kola Sobbar did not influence the choice of the date for Sámi People's Day, as the assembly existed only during the late 1800s and was largely forgotten until the early 2000s.

🔗 Video games

4X is a genre of strategy-based video and board games in which players control an empire and "eXplore, eXpand, eXploit, and eXterminate". The term was coined by Alan Emrich in his September 1993 preview of Master of Orion for Computer Gaming World. Since then, others have adopted the term to describe games of similar scope and design.

4X computer games are noted for their deep, complex gameplay. Emphasis is placed upon economic and technological development, as well as a range of non-military routes to supremacy. Games can take a long time to complete since the amount of micromanagement needed to sustain an empire increases as the empire grows. 4X games are sometimes criticized for becoming tedious for these reasons, and several games have attempted to address these concerns by limiting micromanagement, with varying degrees of success.

The earliest 4X games borrowed ideas from board games and 1970s text-based computer games. The first 4X computer games were turn-based, but real-time 4X games are not uncommon. Many 4X computer games were published in the mid-1990s, but were later outsold by other types of strategy games. Sid Meier's Civilization is an important example from this formative era, and popularized the level of detail that later became a staple of the genre. In the new millennium, several 4X releases have become critically and commercially successful.

In the board (and card) game domain, 4X is less of a distinct genre, in part because of the practical constraints of components and playing time. The Civilization board game that gave rise to Sid Meier's Civilization computer game, for instance, has no exploration and no extermination. Unless extermination is targeted at non-player entities, it tends to be either nearly impossible (because of play balance mechanisms, since player elimination is usually considered an undesirable feature) or certainly unachievable (because victory conditions are triggered before extermination can be completed) in board games.

🔗 Law 🔗 Philosophy 🔗 Philosophy/Logic 🔗 Writing

Argumentation theory is the interdisciplinary study of how conclusions can be supported or undermined by premises through logical reasoning. With historical origins in logic, dialectic, and rhetoric, argumentation theory includes the arts and sciences of civil debate, dialogue, conversation, and persuasion. It studies rules of inference, logic, and procedural rules in both artificial and real-world settings.

Argumentation includes various forms of dialogue such as deliberation and negotiation which are concerned with collaborative decision-making procedures. It also encompasses eristic dialogue, the branch of social debate in which victory over an opponent is the primary goal, and didactic dialogue used for teaching. This discipline also studies the means by which people can express and rationally resolve or at least manage their disagreements.

Argumentation is a daily occurrence, such as in public debate, science, and law. For example in law, in courts by the judge, the parties and the prosecutor, in presenting and testing the validity of evidences. Also, argumentation scholars study the post hoc rationalizations by which organizational actors try to justify decisions they have made irrationally.

Argumentation is one of four rhetorical modes (also known as modes of discourse), along with exposition, description, and narration.

🔗 Computer science 🔗 Science Fiction 🔗 Systems

Swarm intelligence (SI) is the collective behavior of decentralized, self-organized systems, natural or artificial. The concept is employed in work on artificial intelligence. The expression was introduced by Gerardo Beni and Jing Wang in 1989, in the context of cellular robotic systems.

SI systems consist typically of a population of simple agents or boids interacting locally with one another and with their environment. The inspiration often comes from nature, especially biological systems. The agents follow very simple rules, and although there is no centralized control structure dictating how individual agents should behave, local, and to a certain degree random, interactions between such agents lead to the emergence of "intelligent" global behavior, unknown to the individual agents. Examples of swarm intelligence in natural systems include ant colonies, bird flocking, hawks hunting, animal herding, bacterial growth, fish schooling and microbial intelligence.

The application of swarm principles to robots is called swarm robotics, while 'swarm intelligence' refers to the more general set of algorithms. 'Swarm prediction' has been used in the context of forecasting problems. Similar approaches to those proposed for swarm robotics are considered for genetically modified organisms in synthetic collective intelligence.

🔗 Syria

The Hurrian songs are a collection of music inscribed in cuneiform on clay tablets excavated from the ancient Amorite-Canaanite city of Ugarit, a headland in northern Syria, which date to approximately 1400 BCE. One of these tablets, which is nearly complete, contains the Hurrian hymn to Nikkal (also known as the Hurrian cult hymn or A Zaluzi to the Gods, or simply h.6), making it the oldest surviving substantially complete work of notated music in the world. While the composers' names of some of the fragmentary pieces are known, h.6 is an anonymous work.

🔗 Biography 🔗 Bangladesh 🔗 Architecture 🔗 Skyscrapers 🔗 Civil engineering 🔗 Chicago 🔗 Illinois

Fazlur Rahman Khan (Bengali: ফজলুর রহমান খান, Fozlur Rôhman Khan) (3 April 1929 – 27 March 1982) was a Bangladeshi-American structural engineer and architect, who initiated important structural systems for skyscrapers. Considered the "father of tubular designs" for high-rises, Khan was also a pioneer in computer-aided design (CAD). He was the structural engineer of the Sears Tower working with Architect Bruce Graham, since renamed Willis Tower, the tallest building in the world from 1973 until 1998, and the 100-story John Hancock Center.

Khan, more than any other individual, ushered in a renaissance in skyscraper construction during the second half of the 20th century. He has been called the "Einstein of structural engineering" and the "Greatest Structural Engineer of the 20th Century" for his innovative use of structural systems that remain fundamental to modern skyscraper design and construction. In his honor, the Council on Tall Buildings and Urban Habitat established the Fazlur Khan Lifetime Achievement Medal, as one of their CTBUH Skyscraper Awards.

Although best known for skyscrapers, Khan was also an active designer of other kinds of structures, including the Hajj airport terminal, the McMath–Pierce solar telescope, and several stadium structures.