Gabriel Andrew Dirac (13 March 1925 – 20 July 1984) was a Hungarian/British mathematician who mainly worked 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 ...
.
He served as
Erasmus Smith's Professor of Mathematics
The Erasmus Smith's Professor of Mathematics at Trinity College Dublin is one of two endowed mathematics positions at Trinity College Dublin (TCD), the other being the Donegall Lectureship at Trinity College Dublin. It was founded in 1762 and fun ...
at
Trinity College Dublin
, name_Latin = Collegium Sanctae et Individuae Trinitatis Reginae Elizabethae juxta Dublin
, motto = ''Perpetuis futuris temporibus duraturam'' (Latin)
, motto_lang = la
, motto_English = It will last i ...
1964-1966. In 1952, he gave a sufficient condition for a graph to contain a
Hamiltonian circuit
In the mathematical field of graph theory, a Hamiltonian path (or traceable path) is a path in an undirected or directed graph that visits each vertex exactly once. A Hamiltonian cycle (or Hamiltonian circuit) is a cycle that visits each vertex e ...
. The previous year, he conjectured that n points in the plane, not all collinear, must span at least
two-point lines, where
is the largest integer not exceeding
. This conjecture was proven true when n is sufficiently large by
Green
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 Nanometre, nm. In subtractive color systems, used in painting and color printing, it is created by ...
and
Tao
''Tao'' or ''Dao'' is the natural order of the universe, whose character one's intuition must discern to realize the potential for individual wisdom, as conceived in the context of East Asian philosophy, East Asian religions, or any other philo ...
in 2012.
Education
Dirac started his studies at
St John's College, Cambridge
St John's College is a Colleges of the University of Cambridge, constituent college of the University of Cambridge founded by the House of Tudor, Tudor matriarch Lady Margaret Beaufort. In constitutional terms, the college is a charitable corpo ...
in 1942, but by 1942 the war saw him serving in the aircraft industry.
[ He received his MA in 1949, and moved to the ]University of London
The University of London (UoL; abbreviated as Lond or more rarely Londin in post-nominals) is a federal public research university located in London, England, United Kingdom. The university was established by royal charter in 1836 as a degree ...
, getting his Ph.D. "On the Colouring of Graphs: Combinatorial topology of Linear Complexes" there under Richard Rado
Richard Rado FRS (28 April 1906 – 23 December 1989) was a German-born British mathematician whose research concerned combinatorics and graph theory. He was Jewish and left Germany to escape Nazi persecution. He earned two PhDs: in 1933 from th ...
.
Career
Dirac's main academic positions were at the King's College London
King's College London (informally King's or KCL) is a public research university located in London, England. King's was established by royal charter in 1829 under the patronage of King George IV and the Duke of Wellington. In 1836, King's ...
(1948-1954), University of Toronto
The University of Toronto (UToronto or U of T) is a public research university in Toronto, Ontario, Canada, located on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution ...
(1952-1953), University of Vienna
The University of Vienna (german: Universität Wien) is a public research university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world. With its long and rich histor ...
(1954-1958), University of Hamburg
The University of Hamburg (german: link=no, Universität Hamburg, also referred to as UHH) is a public research university in Hamburg, Germany. It was founded on 28 March 1919 by combining the previous General Lecture System ('' Allgemeines Vor ...
(1958-1963), Trinity College Dublin
, name_Latin = Collegium Sanctae et Individuae Trinitatis Reginae Elizabethae juxta Dublin
, motto = ''Perpetuis futuris temporibus duraturam'' (Latin)
, motto_lang = la
, motto_English = It will last i ...
(Erasmus Smith's Professor of Mathematics
The Erasmus Smith's Professor of Mathematics at Trinity College Dublin is one of two endowed mathematics positions at Trinity College Dublin (TCD), the other being the Donegall Lectureship at Trinity College Dublin. It was founded in 1762 and fun ...
, 1964-1966), University of Wales at Swansea
, former_names=University College of Swansea, University of Wales Swansea
, motto= cy, Gweddw crefft heb ei dawn
, mottoeng="Technical skill is bereft without culture"
, established=1920 – University College of Swansea 1996 – University of Wa ...
(1967-1970), and Aarhus University
Aarhus University ( da, Aarhus Universitet, abbreviated AU) is a public research university with its main campus located in Aarhus, Denmark. It is the second largest and second oldest university in Denmark. The university is part of the Coimbra Gr ...
(1970-1984).[
]
Family
He was born Balázs Gábor in Budapest
Budapest (, ; ) is the capital and most populous city of Hungary. It is the ninth-largest city in the European Union by population within city limits and the second-largest city on the Danube river; the city has an estimated population ...
, to Richárd Balázs, a military officer and businessman, and Margit "Manci" Wigner (sister of Eugene Wigner
Eugene Paul "E. P." Wigner ( hu, Wigner Jenő Pál, ; November 17, 1902 – January 1, 1995) was a Hungarian-American theoretical physicist who also contributed to mathematical physics. He received the Nobel Prize in Physics in 1963 "for his con ...
). When his mother married Paul Dirac
Paul Adrien Maurice Dirac (; 8 August 1902 – 20 October 1984) was an English theoretical physicist who is regarded as one of the most significant physicists of the 20th century. He was the Lucasian Professor of Mathematics at the Univer ...
in 1937, he and his sister resettled in England and were formally adopted, changing their family name to Dirac. He married Rosemari Dirac and they had four children together: Meike, Barbara, Holger and Annette.
See also
*Dirac's theorem on Hamiltonian cycles
In the mathematical field of graph theory, a Hamiltonian path (or traceable path) is a path in an undirected or directed graph that visits each vertex exactly once. A Hamiltonian cycle (or Hamiltonian circuit) is a cycle that visits each vertex ...
*Dirac's theorem on chordal graphs
In the mathematics, mathematical area of graph theory, a chordal graph is one in which all cycle (graph theory), cycles of four or more vertex (graph theory), vertices have a ''chord'', which is an edge (graph theory), edge that is not part of the ...
* Dirac's theorem on cycles in -connected graphs
Notes
References
* L. Døvling Andersen, I. Tafteberg Jakobsen, C. Thomassen, B. Toft, and P. Vestergaard (eds.)
''Graph Theory in Memory of G.A. Dirac''
Annals of Discrete Mathematics, volume 41, North-Holland, 1989. .
{{DEFAULTSORT:Dirac, Gabriel Andrew
20th-century Hungarian mathematicians
Graph theorists
Alumni of the University of London
1925 births
1984 deaths
Hungarian Jews
Paul Dirac
Aarhus University faculty
Academics of Trinity College Dublin