Alfred Gray (mathematician)
Alfred Gray (October 22, 1939 – October 27, 1998) was an American mathematician whose main research interests were in differential geometry. He also made contributions in the fields of complex variables and differential equations. Short biography Alfred Gray was born in Dallas, Texas to Alfred James Gray & Eloise Evans and studied mathematics at the University of Kansas. He received a Ph.D. from the University of California, Los Angeles in 1964 and spent four years at University of California, Berkeley. From 1970–1998 he was a professor at the University of Maryland, College Park. He died in Bilbao, Spain of a heart attack while working with students in a computer lab at Colegio Mayor Miguel de Unamuno around 4 AM, on October 27, 1998. Mathematical contributions In the broad area of differential geometry, he made specific contributions in classifying various types of geometrical structures, such as (Kähler manifolds and almost Hermitian manifolds). Gray introduced the ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Nearly Kähler Manifold
In mathematics, a nearly Kähler manifold is an almost Hermitian manifold M, with almost complex structure J, such that the (2,1)-tensor \nabla J is skew-symmetric. So, : (\nabla_X J)X =0 for every vector field X on M. In particular, a Kähler manifold is nearly Kähler. The converse is not true. For example, the nearly Kähler six-sphere S^6 is an example of a nearly Kähler manifold that is not Kähler. The familiar almost complex structure on the six-sphere is not induced by a complex atlas on S^6. Usually, non Kählerian nearly Kähler manifolds are called "strict nearly Kähler manifolds". Nearly Kähler manifolds, also known as almost Tachibana manifolds, were studied by Shun-ichi Tachibana in 1959 and then by Alfred Gray from 1970 on. For example, it was proved that any 6-dimensional strict nearly Kähler manifold is an Einstein manifold In differential geometry and mathematical physics, an Einstein manifold is a Riemannian or pseudo-Riemannian differentiable mani ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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University Of Maryland, College Park Faculty
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. ''University'' is derived from the Latin phrase ''universitas magistrorum et scholarium'', which roughly means "community of teachers and scholars". Universities typically offer both undergraduate and postgraduate programs. The first universities in Europe were established by Catholic Church monks. The University of Bologna (), Italy, which was founded in 1088, is the first university in the sense of: *being a high degree-awarding institute. *using the word ''universitas'' (which was coined at its foundation). *having independence from the ecclesiastic schools and issuing secular as well as non-secular degrees (with teaching conducted by both clergy and non-clergy): grammar, rhetoric, logic, theology, canon law, notarial law.Hunt Janin: "The university in medieval life, 1179–1499", McFarland, 2008, , p. 55f.de Ridder-Symoens, Hild ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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1998 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 * Deaths by year {{DEFAULTSORT:deaths by year ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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1939 Births
This year also marks the start of the Second World War, the largest and deadliest conflict in human history. Events Below, the events of World War II have the "WWII" prefix. January * January 1 ** Third Reich *** Jews are forbidden to work with Germans. *** The Youth Protection Act was passed on April 30, 1938 and the Working Hours Regulations came into effect. *** The Jews name change decree has gone into effect. ** The rest of the world *** In Spain, it becomes a duty of all young women under 25 to complete compulsory work service for one year. *** First edition of the Vienna New Year's Concert. *** The company of technology and manufacturing scientific instruments Hewlett-Packard, was founded in a garage in Palo Alto, California, by William (Bill) Hewlett and David Packard. This garage is now considered the birthplace of Silicon Valley. *** Sydney, in Australia, records temperature of 45 ˚C, the highest record for the city. *** Philipp Etter took over ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Ordinary Differential Equation
In mathematics, an ordinary differential equation (ODE) is a differential equation whose unknown(s) consists of one (or more) function(s) of one variable and involves the derivatives of those functions. The term ''ordinary'' is used in contrast with the term partial differential equation which may be with respect to ''more than'' one independent variable. Differential equations A linear differential equation is a differential equation that is defined by a linear polynomial in the unknown function and its derivatives, that is an equation of the form :a_0(x)y +a_1(x)y' + a_2(x)y'' +\cdots +a_n(x)y^+b(x)=0, where , ..., and are arbitrary differentiable functions that do not need to be linear, and are the successive derivatives of the unknown function of the variable . Among ordinary differential equations, linear differential equations play a prominent role for several reasons. Most elementary and special functions that are encountered in physics and applied mathem ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Computer Graphics
Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great deal of specialized hardware and software has been developed, with the displays of most devices being driven by graphics hardware, computer graphics hardware. It is a vast and recently developed area of computer science. The phrase was coined in 1960 by computer graphics researchers Verne Hudson and William Fetter of Boeing. It is often abbreviated as CG, or typically in the context of film as Computer-generated imagery, computer generated imagery (CGI). The non-artistic aspects of computer graphics are the subject of Computer graphics (computer science), computer science research. Some topics in computer graphics include user interface design, sprite (graphics), sprite graphics, Rendering (computer graphics), rendering, ray tracing (graphics) ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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German Language
German ( ) is a West Germanic language mainly spoken in Central Europe. It is the most widely spoken and official or co-official language in Germany, Austria, Switzerland, Liechtenstein, and the Italian province of South Tyrol. It is also a co-official language of Luxembourg and Belgium, as well as a national language in Namibia. Outside Germany, it is also spoken by German communities in France ( Bas-Rhin), Czech Republic (North Bohemia), Poland ( Upper Silesia), Slovakia (Bratislava Region), and Hungary ( Sopron). German is most similar to other languages within the West Germanic language branch, including Afrikaans, Dutch, English, the Frisian languages, Low German, Luxembourgish, Scots, and Yiddish. It also contains close similarities in vocabulary to some languages in the North Germanic group, such as Danish, Norwegian, and Swedish. German is the second most widely spoken Germanic language after English, which is also a West Germanic language. German ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Russian Language
Russian (russian: русский язык, russkij jazyk, link=no, ) is an East Slavic language mainly spoken in Russia. It is the native language of the Russians, and belongs to the Indo-European language family. It is one of four living East Slavic languages, and is also a part of the larger Balto-Slavic languages. Besides Russia itself, Russian is an official language in Belarus, Kazakhstan, and Kyrgyzstan, and is used widely as a lingua franca throughout Ukraine, the Caucasus, Central Asia, and to some extent in the Baltic states. It was the ''de facto'' language of the former Soviet Union, Constitution and Fundamental Law of the Union of Soviet Socialist Republics, 1977: Section II, Chapter 6, Article 36 and continues to be used in public life with varying proficiency in all of the post-Soviet states. Russian has over 258 million total speakers worldwide. It is the most spoken Slavic language, and the most spoken native language in Europe, as well as the ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Italian Language
Italian (''italiano'' or ) is a Romance language of the Indo-European language family that evolved from the Vulgar Latin of the Roman Empire. Together with Sardinian, Italian is the least divergent language from Latin. Spoken by about 85 million people (2022), Italian is an official language in Italy, Switzerland ( Ticino and the Grisons), San Marino, and Vatican City. It has an official minority status in western Istria (Croatia and Slovenia). Italian is also spoken by large immigrant and expatriate communities in the Americas and Australia.Ethnologue report for language code:ita (Italy) – Gordon, Raymond G., Jr. (ed.), 2005. Ethnologue: Languages of the World, Fifteenth edition. Dallas, Tex.: SIL International. Online version ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |