Piers Bohl
Piers Bohl (23 October 1865 – 25 December 1921) was a Latvian mathematician, who worked in differential equations, topology and quasi-periodic functions. He was born in 1865 in Walk, Livonia, in the family of a poor Baltic German merchant. In 1884, after graduating from a German school in Viljandi, he entered the faculty of physics and mathematics at the University of Tartu. In 1893 Bohl was awarded his Master's degree. This was for an investigation of quasi-periodic functions. The notion of quasi-periodic functions was generalised still further by Harald Bohr when he introduced almost-periodic functions. He has been the first to prove the three-dimensional case of the Brouwer fixed-point theorem Brouwer's fixed-point theorem is a fixed-point theorem in topology, named after L. E. J. (Bertus) Brouwer. It states that for any continuous function f mapping a compact convex set to itself there is a point x_0 such that f(x_0)=x_0. The simples ..., but his work was not noticed ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Walk, Livonia
Walk was the historical German name for the town that is since 1920 divided into Valga in Estonia and Valka in Latvia. After 1419 it was the seat of the Landtag of the Livonian Confederation. See also *List of German exonyms for places in Estonia *List of German exonyms for places in Latvia This article contains a list of exonyms in German for geographical places in the current and previous territory of Latvia. A large part of the Latgale region of Latvia was included in the Polish–Lithuanian Commonwealth (1569-1772), later in the ... References Livonian Confederation {{Vidzeme-geo-stub ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Harald Bohr
Harald August Bohr (22 April 1887 – 22 January 1951) was a Danish mathematician and footballer. After receiving his doctorate in 1910, Bohr became an eminent mathematician, founding the field of almost periodic functions. His brother was the Nobel Prize-winning physicist Niels Bohr. He was a member of the Danish national football team for the 1908 Summer Olympics, where he won a silver medal. Biography Bohr was born in 1887 to Christian Bohr, a professor of physiology, from a Lutheran background, and Ellen Adler Bohr, a woman from a wealthy Jewish family of local renown. Harald had a close relationship with his elder brother, which ''The Times'' likened to that between Captain Cuttle and Captain Bunsby in Charles Dickens' ''Dombey and Son''. Mathematical career Like his father and brother before him, in 1904 Bohr enrolled at the University of Copenhagen, where he studied mathematics, obtaining his master's degree in 1909 and his doctorate a year later. Among his tutors were Hie ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Latvian Mathematicians
Latvian may refer to: *Something of, from, or related to Latvia **Latvians, a Baltic ethnic group, native to what is modern-day Latvia and the immediate geographical region **Latvian language, also referred to as Lettish **Latvian cuisine **Latvian culture The culture of Latvia combines traditional Latvian and Livonian heritage with influences of the country's varied historical heritage. History The area of Latvia has been inhabited since 9000 BC. Baltic tribes, the ancestors of present-day ... **Latvian horse *Latvian Gambit, an opening in chess See also *Latvia (other) * {{disambiguation Language and nationality disambiguation pages ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Baltic-German People
Baltic Germans (german: Deutsch-Balten or , later ) were ethnic German inhabitants of the eastern shores of the Baltic Sea, in what today are Estonia and Latvia. Since their coerced resettlement in 1939, Baltic Germans have markedly declined as a geographically determined ethnic group. However, it is estimated that several thousand people with some form of (Baltic) German identity still reside in Latvia and Estonia. Since the Middle Ages, native German-speakers formed the majority of merchants and clergy, and the large majority of the local landowning nobility who effectively constituted a ruling class over indigenous Latvian and Estonian non-nobles. By the time a distinct Baltic German ethnic identity began emerging in the 19th century, the majority of self-identifying Baltic Germans were non-nobles belonging mostly to the urban and professional middle class. In the 12th and 13th centuries, Catholic German traders and crusaders (''see '') began settling in the eastern Ba ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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People From Kreis Walk
A person ( : people) is a being that has certain capacities or attributes such as reason, morality, consciousness or self-consciousness, and being a part of a culturally established form of social relations such as kinship, ownership of property, or legal responsibility. The defining features of personhood and, consequently, what makes a person count as a person, differ widely among cultures and contexts. In addition to the question of personhood, of what makes a being count as a person to begin with, there are further questions about personal identity and self: both about what makes any particular person that particular person instead of another, and about what makes a person at one time the same person as they were or will be at another time despite any intervening changes. The plural form "people" is often used to refer to an entire nation or ethnic group (as in "a people"), and this was the original meaning of the word; it subsequently acquired its use as a plural form of per ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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People From Valka
A person ( : people) is a being that has certain capacities or attributes such as reason, morality, consciousness or self-consciousness, and being a part of a culturally established form of social relations such as kinship, ownership of property, or legal responsibility. The defining features of personhood and, consequently, what makes a person count as a person, differ widely among cultures and contexts. In addition to the question of personhood, of what makes a being count as a person to begin with, there are further questions about personal identity and self: both about what makes any particular person that particular person instead of another, and about what makes a person at one time the same person as they were or will be at another time despite any intervening changes. The plural form "people" is often used to refer to an entire nation or ethnic group (as in "a people"), and this was the original meaning of the word; it subsequently acquired its use as a plural form of ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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1921 Deaths
Nineteen or 19 may refer to: * 19 (number), the natural number following 18 and preceding 20 * one of the years 19 BC, AD 19, 1919, 2019 Films * ''19'' (film), a 2001 Japanese film * ''Nineteen'' (film), a 1987 science fiction film Music * 19 (band), a Japanese pop music duo Albums * ''19'' (Adele album), 2008 * ''19'', a 2003 album by Alsou * ''19'', a 2006 album by Evan Yo * ''19'', a 2018 album by MHD * ''19'', one half of the double album ''63/19'' by Kool A.D. * ''Number Nineteen'', a 1971 album by American jazz pianist Mal Waldron * ''XIX'' (EP), a 2019 EP by 1the9 Songs * "19" (song), a 1985 song by British musician Paul Hardcastle. * "Nineteen", a song by Bad4Good from the 1992 album '' Refugee'' * "Nineteen", a song by Karma to Burn from the 2001 album ''Almost Heathen''. * "Nineteen" (song), a 2007 song by American singer Billy Ray Cyrus. * "Nineteen", a song by Tegan and Sara from the 2007 album '' The Con''. * "XIX" (song), a 2014 song by Slipknot ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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1865 Births
Events January–March * January 4 – The New York Stock Exchange opens its first permanent headquarters at 10-12 Broad near Wall Street, in New York City. * January 13 – American Civil War : Second Battle of Fort Fisher: United States forces launch a major amphibious assault against the last seaport held by the Confederates, Fort Fisher, North Carolina. * January 15 – American Civil War: United States forces capture Fort Fisher. * January 31 ** The Thirteenth Amendment to the United States Constitution (conditional prohibition of slavery and involuntary servitude) passes narrowly, in the House of Representatives. ** American Civil War: Confederate General Robert E. Lee becomes general-in-chief. * February ** American Civil War: Columbia, South Carolina burns, as Confederate forces flee from advancing Union forces. * February 3 – American Civil War : Hampton Roads Conference: Union and Confederate leaders discuss peace terms. * February 8 ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Brouwer Fixed-point Theorem
Brouwer's fixed-point theorem is a fixed-point theorem in topology, named after L. E. J. (Bertus) Brouwer. It states that for any continuous function f mapping a compact convex set to itself there is a point x_0 such that f(x_0)=x_0. The simplest forms of Brouwer's theorem are for continuous functions f from a closed interval I in the real numbers to itself or from a closed disk D to itself. A more general form than the latter is for continuous functions from a convex compact subset K of Euclidean space to itself. Among hundreds of fixed-point theorems, Brouwer's is particularly well known, due in part to its use across numerous fields of mathematics. In its original field, this result is one of the key theorems characterizing the topology of Euclidean spaces, along with the Jordan curve theorem, the hairy ball theorem, the invariance of dimension and the Borsuk–Ulam theorem. This gives it a place among the fundamental theorems of topology. The theorem is also used for proving ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Almost-periodic Function
In mathematics, an almost periodic function is, loosely speaking, a function of a real number that is periodic to within any desired level of accuracy, given suitably long, well-distributed "almost-periods". The concept was first studied by Harald Bohr and later generalized by Vyacheslav Stepanov, Hermann Weyl and Abram Samoilovitch Besicovitch, amongst others. There is also a notion of almost periodic functions on locally compact abelian groups, first studied by John von Neumann. Almost periodicity is a property of dynamical systems that appear to retrace their paths through phase space, but not exactly. An example would be a planetary system, with planets in orbits moving with periods that are not commensurable (i.e., with a period vector that is not proportional to a vector of integers). A theorem of Kronecker from diophantine approximation can be used to show that any particular configuration that occurs once, will recur to within any specified accuracy: if we wait l ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Viljandi
Viljandi (, german: Fellin, sv, Fellin) is a town and municipality in southern Estonia with a population of 17,407 in 2019. It is the capital of Viljandi County and is geographically located between two major Estonian cities, Pärnu and Tartu. The town was first mentioned in 1283, upon being granted its town charter by Wilhelm von Endorpe. The town became a member of the Hanseatic League at the beginning of the 14th century, and is one of five Estonian towns and cities in the league. The once influential Estonian newspaper '' Sakala'' was founded in Viljandi in 1878. Symbols The flag of Viljandi is bi-coloured, its upper part light blue and lower part white. The city's shield-shaped coat of arms is light blue, with a white rose in the middle. Viljandi is the white rose city – in midsummer there are 720 white roses flowering in front of the city hall, planted for the town's anniversary in 2003. In summer, the White Rose Day is celebrated in Viljandi. History First record ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Riga
Riga (; lv, Rīga , liv, Rīgõ) is the capital and largest city of Latvia and is home to 605,802 inhabitants which is a third of Latvia's population. The city lies on the Gulf of Riga at the mouth of the Daugava river where it meets the Baltic Sea. Riga's territory covers and lies above sea level, on a flat and sandy plain. Riga was founded in 1201 and is a former Hanseatic League member. Riga's historical centre is a UNESCO World Heritage Site, noted for its Art Nouveau/Jugendstil architecture and 19th century wooden architecture. Riga was the European Capital of Culture in 2014, along with Umeå in Sweden. Riga hosted the 2006 NATO Summit, the Eurovision Song Contest 2003, the 2006 IIHF Men's World Ice Hockey Championships, 2013 World Women's Curling Championship and the 2021 IIHF World Championship. It is home to the European Union's office of European Regulators for Electronic Communications (BEREC). In 2017, it was named the European Region of Gastronomy. I ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |