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Nikolai Aleksandrovich Shanin
Nikolai Aleksandrovich Shanin (russian: Николай Александрович Шанин) (25 May 1919 Pskov – 17 September 2011) was a Russian mathematician who worked on topology and constructive mathematics. He introduced the delta-system lemma and the caliber In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel Gauge (firearms) , bore – regardless of how or where the bore is measured and whether the f ... of a topological space. Further reading * * External links *Nikolai Aleksandrovich Shaninat the Steklov Institute of Mathematics at St. Petersburg {{DEFAULTSORT:Shanin, Nikolai Aleksandrovich Russian mathematicians 1919 births 2011 deaths People from Pskov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pskov
Pskov ( rus, Псков, a=pskov-ru.ogg, p=pskof; see also names in other languages) is a city in northwestern Russia and the administrative center of Pskov Oblast, located about east of the Estonian border, on the Velikaya River. Population: Pskov is one of the oldest cities in Russia. It served as the capital of the Pskov Republic and was a trading post of the Hanseatic League before it came under the control of the Grand Duchy of Moscow. History Early history Pskov is one of the oldest cities in Russia. The name of the city, originally Pleskov (historic Russian spelling , ''Plěskov''), may be loosely translated as "he townof purling waters". It was historically known in English as Plescow. Its earliest mention comes in 903, which records that Igor of Kiev married a local lady, Olga (later Saint Olga of Kiev). Pskovians sometimes take this year as the city's foundation date, and in 2003 a great jubilee took place to celebrate Pskov's 1,100th anniversary. The f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topology
In mathematics, topology (from the Greek language, Greek words , and ) is concerned with the properties of a mathematical object, geometric object that are preserved under Continuous function, continuous Deformation theory, deformations, such as Stretch factor, stretching, Twist (mathematics), twisting, crumpling, and bending; that is, without closing holes, opening holes, tearing, gluing, or passing through itself. A topological space is a set (mathematics), set endowed with a structure, called a ''Topology (structure), topology'', which allows defining continuous deformation of subspaces, and, more generally, all kinds of continuity (mathematics), continuity. Euclidean spaces, and, more generally, metric spaces are examples of a topological space, as any distance or metric defines a topology. The deformations that are considered in topology are homeomorphisms and homotopy, homotopies. A property that is invariant under such deformations is a topological property. Basic exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constructive Mathematics
In the philosophy of mathematics, constructivism asserts that it is necessary to find (or "construct") a specific example of a mathematical object in order to prove that an example exists. Contrastingly, in classical mathematics, one can prove the existence of a mathematical object without "finding" that object explicitly, by assuming its non-existence and then deriving a contradiction from that assumption. Such a proof by contradiction might be called non-constructive, and a constructivist might reject it. The constructive viewpoint involves a verificational interpretation of the existential quantifier, which is at odds with its classical interpretation. There are many forms of constructivism. These include the program of intuitionism founded by Brouwer, the finitism of Hilbert and Bernays, the constructive recursive mathematics of Shanin and Markov, and Bishop's program of constructive analysis. Constructivism also includes the study of constructive set theories such as CZF ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta-system Lemma
In the mathematical fields of set theory and extremal combinatorics, a sunflower or \Delta-system is a collection of sets whose pairwise intersection is constant. This constant intersection is called the kernel of the sunflower. The main research question arising in relation to sunflowers is: under what conditions does there exist a ''large'' sunflower (a sunflower with many sets) in a given collection of sets? The \Delta-lemma, sunflower lemma, and the Erdős-Rado sunflower conjecture give successively weaker conditions which would imply the existence of a large sunflower in a given collection, with the latter being one of the most famous open problems of extremal combinatorics. Formal definition Suppose W is a set system over U, that is, a collection of subsets of a set U. The collection W is a ''sunflower'' (or ''\Delta-system'') if there is a subset S of U such that for each distinct A and B in W, we have A \cap B = S. In other words, a set system or collection of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caliber (mathematics)
In mathematics, the caliber or calibre of a topological space ''X'' is a cardinal Cardinal or The Cardinal may refer to: Animals * Cardinal (bird) or Cardinalidae, a family of North and South American birds **''Cardinalis'', genus of cardinal in the family Cardinalidae **''Cardinalis cardinalis'', or northern cardinal, the ... ''κ'' such that for every set of ''κ'' nonempty open subsets of ''X'' there is some point of ''X'' contained in ''κ'' of these subsets. This concept was introduced by . There is a similar concept for posets. A pre-caliber of a poset ''P'' is a cardinal ''κ'' such that for any collection of elements of ''P'' indexed by ''κ'', there is a subcollection of cardinality ''κ'' that is centered. Here a subset of a poset is called centered if for any finite subset there is an element of the poset less than or equal to all of them. References * *{{citation, mr=0027310 , last=Shanin, first= N. A. , title=On the product of topological spaces , journal=Tru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Russian Mathematicians
Russian(s) refers to anything related to Russia, including: *Russians (, ''russkiye''), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *Rossiyane (), Russian language term for all citizens and people of Russia, regardless of ethnicity *Russophone, Russian-speaking person (, ''russkogovoryashchy'', ''russkoyazychny'') *Russian language, the most widely spoken of the Slavic languages *Russian alphabet *Russian cuisine *Russian culture *Russian studies Russian may also refer to: *Russian dressing *''The Russians'', a book by Hedrick Smith *Russian (comics), fictional Marvel Comics supervillain from ''The Punisher'' series *Russian (solitaire), a card game * "Russians" (song), from the album ''The Dream of the Blue Turtles'' by Sting *"Russian", from the album ''Tubular Bells 2003'' by Mike Oldfield *"Russian", from the album '' '' by Caravan Palace *Nik Russian, the perpetrator of a con committed in 2002 *The South African name for a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1919 Births
Events January * January 1 ** The Czechoslovak Legions occupy much of the self-proclaimed "free city" of Pressburg (now Bratislava), enforcing its incorporation into the new republic of Czechoslovakia. ** HMY ''Iolaire'' sinks off the coast of the Hebrides; 201 people, mostly servicemen returning home to Lewis and Harris, are killed. * January 2– 22 – Russian Civil War: The Red Army's Caspian-Caucasian Front begins the Northern Caucasus Operation against the White Army, but fails to make progress. * January 3 – The Faisal–Weizmann Agreement is signed by Emir Faisal (representing the Arab Kingdom of Hejaz) and Zionist leader Chaim Weizmann, for Arab–Jewish cooperation in the development of a Jewish homeland in Palestine, and an Arab nation in a large part of the Middle East. * January 5 – In Germany: ** Spartacist uprising in Berlin: The Marxist Spartacus League, with the newly formed Communist Party of Germany and the Independent Social De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2011 Deaths
This is a list of deaths of notable people, organised by year. New deaths articles are added to their respective month (e.g., Deaths in ) and then linked here. 2022 2021 2020 2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 See also * Lists of deaths by day The following pages, corresponding to the Gregorian calendar, list the historical events, births, deaths, and holidays and observances of the specified day of the year: Footnotes See also * Leap year * List of calendars * List of non-standard ... * Deaths by year {{DEFAULTSORT:deaths by year ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
