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András Gyárfás
András Gyárfás (born 1945) is a Hungarian mathematician who specializes in the study of graph theory. He is famous for two conjectures: * Together with Paul Erdős he conjectured what is now called the Erdős–Gyárfás conjecture which states that any graph with minimum degree 3 contains a simple cycle whose length is a power of two. * He and David Sumner independently formulated the Gyárfás–Sumner conjecture according to which, for every tree ''T'', the ''T''-free graphs are χ-bounded. Gyárfás began working as a researcher for the Computer and Automation Research Institute of the Hungarian Academy of Sciences in 1968. He earned a candidate degree in 1980, and a doctorate (Dr. Math. Sci.) in 1992. He won the Géza Grünwald Commemorative Prize for young researchers of the János Bolyai Mathematical Society in 1978. He was co-author with Paul Erdős on 15 papers, and thus has Erdős number The Erdős number () describes the "collaborative distance" betwee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hungary
Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and Slovenia to the southwest, and Austria to the west. Hungary has a population of nearly 9 million, mostly ethnic Hungarians and a significant Romani minority. Hungarian, the official language, is the world's most widely spoken Uralic language and among the few non-Indo-European languages widely spoken in Europe. Budapest is the country's capital and largest city; other major urban areas include Debrecen, Szeged, Miskolc, Pécs, and Győr. The territory of present-day Hungary has for centuries been a crossroads for various peoples, including Celts, Romans, Germanic tribes, Huns, West Slavs and the Avars. The foundation of the Hungarian state was established in the late 9th century AD with the conquest of the Carpathian Basin by Hungar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
χ-bounded
In graph theory, a \chi-bounded family \mathcal of graphs is one for which there is some function c such that, for every integer t the graphs in \mathcal with t=\omega(G) (clique number) can be colored with at most c(t) colors. This concept and its notation were formulated by András Gyárfás. The use of the Greek letter chi in the term \chi-bounded is based on the fact that the chromatic number of a graph G is commonly denoted \chi(G). Nontriviality It is not true that the family of all graphs is \chi-bounded. As and showed, there exist triangle-free graphs of arbitrarily large chromatic number, so for these graphs it is not possible to define a finite value of t(3). Thus, \chi-boundedness is a nontrivial concept, true for some graph families and false for others. Specific classes Every class of graphs of bounded chromatic number is (trivially) \chi-bounded, with c(t) equal to the bound on the chromatic number. This includes, for instance, the planar graphs, the bipartite gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1945 Births
1945 marked the end of World War II and the fall of Nazi Germany and the Empire of Japan. It is also the only year in which Nuclear weapon, nuclear weapons Atomic bombings of Hiroshima and Nagasaki, have been used in combat. Events Below, the events of World War II have the "WWII" prefix. January * January 1 – WWII: ** Nazi Germany, Germany begins Operation Bodenplatte, an attempt by the ''Luftwaffe'' to cripple Allies of World War II, Allied air forces in the Low Countries. ** Chenogne massacre: German prisoners are allegedly killed by American forces near the village of Chenogne, Belgium. * January 6 – WWII: A German offensive recaptures Esztergom, Kingdom of Hungary (1920–1946), Hungary from the Russians. * January 12 – WWII: The Soviet Union begins the Vistula–Oder Offensive in Eastern Europe, against the German Army (Wehrmacht), German Army. * January 13 – WWII: The Soviet Union begins the East Prussian Offensive, to eliminate German forces in East Pruss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
21st-century Hungarian Mathematicians
The 1st century was the century spanning AD 1 ( I) through AD 100 ( C) according to the Julian calendar. It is often written as the or to distinguish it from the 1st century BC (or BCE) which preceded it. The 1st century is considered part of the Classical era, epoch, or historical period. The 1st century also saw the appearance of Christianity. During this period, Europe, North Africa and the Near East fell under increasing domination by the Roman Empire, which continued expanding, most notably conquering Britain under the emperor Claudius (AD 43). The reforms introduced by Augustus during his long reign stabilized the empire after the turmoil of the previous century's civil wars. Later in the century the Julio-Claudian dynasty, which had been founded by Augustus, came to an end with the suicide of Nero in AD 68. There followed the famous Year of Four Emperors, a brief period of civil war and instability, which was finally brought to an end by Vespasian, ninth Roman emperor, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erdős Number
The Erdős number () 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. Overview Paul Erdős (1913–1996) was an influential Hungarian mathematician who in the latter part of his life spent a great deal of time writing papers with a large number of colleagues, working on solutions to outstanding mathematical problems. He published more papers during his lifetime (at least 1,525) than any other mathematician in history. (Leonhard Euler published more total pages of mathematics but fewer separate papers: about 800.) Erdős spent a large portion of his later life living out of a suitcase, visiting over 500 collaborators around the world. The idea of the Erdős number was originally created by the mathematician's friends as a tribute to his enormous ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
János Bolyai Mathematical Society
The János Bolyai Mathematical Society (Bolyai János Matematikai Társulat, BJMT) is the Hungarian mathematical society, named after János Bolyai, a 19th-century Hungarian mathematician, a co-discoverer of non-Euclidean geometry. It is the professional society of the Hungarian mathematicians, applied mathematicians, and mathematics teachers. It was founded in 1947, as one of the two successor societies of the Mathematical and Physical Society (Matematikai és Fizikai Társulat) founded in 1891. It is a member-society of the European Mathematical Society. Presidents of the Society * László Rédei (1947–1949) * György Alexits (1949–1963) * György Hajós (1963–1972) * László Fejes Tóth (1972–1975) * Pál Turán (1975–1976) * (1976–1980) * Ákos Császár (1980–1990) * András Hajnal (1990–1996) * Imre Csiszár (1996–2006) * Gyula Katona (2006–2018) * Péter Pál Pálfy (2018–) Periodicals The society publish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Candidate Degree
Candidate of Philosophy can refer to the US degree or status of Candidate in Philosophy (C.Phil. or Ph.C.) granted to Ph.D. students who have been accepted as candidates for that degree, or (as a direct translation) to degrees or former degrees at bachelor's or master's level from some Scandinavian countries. United States In the United States, it is normal for graduate students working toward a doctorate to take coursework followed by examinations (known variously as candidacy examinations, comprehensive examinations or qualifiers) after which they become candidates for the doctorate. At a few institutions, this status is officially recognized either by a degree or some other official title. This is normally intended to be an interim status, prior to the award of a doctorate, not to be confused with the terminal master's degree awarded by some programs to those who leave after their candidacy examination. Some universities grant a Master of Philosophy degree to students who have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hungarian Academy Of Sciences
The Hungarian Academy of Sciences ( hu, Magyar Tudományos Akadémia, MTA) is the most important and prestigious learned society of Hungary. Its seat is at the bank of the Danube in Budapest, between Széchenyi rakpart and Akadémia utca. Its main responsibilities are the cultivation of science, dissemination of scientific findings, supporting research and development, and representing Hungarian science domestically and around the world. History The history of the academy began in 1825 when Count István Széchenyi offered one year's income of his estate for the purposes of a ''Learned Society'' at a district session of the Diet in Pressburg (Pozsony, present Bratislava, seat of the Hungarian Parliament at the time), and his example was followed by other delegates. Its task was specified as the development of the Hungarian language and the study and propagation of the sciences and the arts in Hungarian. It received its current name in 1845. Its central building was inaugurate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Institute For Computer Science And Control
The Institute for Computer Science and Control (in short SZTAKI, hu, Számítástechnikai és Automatizálási Kutatóintézet) is a Hungarian research institute in Budapest, founded in 1964. Scope Its primary tasks include basic and application-oriented research in an interdisciplinary setting in the fields of engineering, computer science, information technology, intelligent systems as well as process control, multimedia and wide area networking. Further tasks of SZTAKI include training, contract-based target research, development and expert support for domestic and foreign industrial, governmental and other partners. The institute also operates a public advice service on knowledge-transfer of up-to-date research results and state-of-the-art technology to university students. SZTAKI has wide external relationships and different groups within the institute work on projects for well-known international and Hungarian companies and the number of European Union projects is also i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tree (graph Theory)
In graph theory In mathematics, graph theory is the study of ''graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of '' vertices'' (also called ''nodes'' or ''points'') which are conne ..., a tree is an undirected graph in which any two Vertex (graph theory), vertices are connected by ''exactly one'' Path (graph theory), path, or equivalently a Connected graph, connected Cycle (graph theory), acyclic undirected graph. A forest is an undirected graph in which any two vertices are connected by ''at most one'' path, or equivalently an acyclic undirected graph, or equivalently a Disjoint union of graphs, disjoint union of trees. A polytreeSee . (or directed tree or oriented treeSee .See . or singly connected networkSee .) is a directed acyclic graph (DAG) whose underlying undirected graph is a tree. A polyforest (or directed forest or oriented forest) is a directed acyclic graph whose underlying undirecte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History One of the earliest known mathematicians were Thales of Miletus (c. 624–c.546 BC); he has been hailed as the first true mathematician and the first known individual to whom a mathematical discovery has been attributed. He is credited with the first use of deductive reasoning applied to geometry, by deriving four corollaries to Thales' Theorem. The number of known mathematicians grew when Pythagoras of Samos (c. 582–c. 507 BC) established the Pythagorean School, whose doctrine it was that mathematics ruled the universe and whose motto was "All is number". It was the Pythagoreans who coined the term "mathematics", and with whom the study of mathematics for its own sake begins. The first woman mathematician recorded by history was Hypati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
