Gabriel Andrew Dirac

Gabriel Andrew Dirac
Born	(1925-03-13)13 March 1925 Budapest
Died	20 July 1984(1984-07-20) (aged 59) Arlesheim
Education	Ph.D.
Alma mater	St John's College, Cambridge University of London
Known for	Graph theory
Scientific career
Fields	Mathematics
Institutions	University of Aarhus, Trinity College Dublin
Thesis	On the Colouring of Graphs: Combinatorial topology of Linear Complexes  (1952)
Doctoral advisor	Richard Rado

Gabriel Andrew Dirac (13 March 1925 – 20 July 1984) was a Hungarian-British mathematician who mainly worked in graph theory. He served as Erasmus Smith's Professor of Mathematics at Trinity College Dublin from 1964 to 1966. In 1952, he gave a sufficient condition for a graph to contain a Hamiltonian circuit. The previous year, he conjectured that n points in the plane, not all collinear, must span at least $\lfloor n/2\rfloor$ two-point lines, where $\lfloor x\rfloor$ is the largest integer not exceeding $x$. This conjecture was proven true when n is sufficiently large by Green and Tao in 2012.

Education

Dirac started his studies at St John's College, Cambridge in 1942, but in that same year the war saw him serving in the aircraft industry. He received his MA in 1949, and moved to the University of London, getting his Ph.D. "On the Colouring of Graphs: Combinatorial topology of Linear Complexes" there under Richard Rado.

Career

Dirac's main academic positions were at the King's College London (1948-1954), University of Toronto (1952-1953), University of Vienna (1954-1958), University of Hamburg (1958-1963), Trinity College Dublin (Erasmus Smith's Professor of Mathematics, 1964-1966), University of Wales at Swansea (1967-1970), and Aarhus University (1970-1984).

Family

He was born Balázs Gábor in Budapest, to Richárd Balázs, a military officer and businessman, and Margit "Manci" Wigner (sister of Eugene Wigner). When his mother married Paul Dirac 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
• Dirac's theorem on chordal graphs
• Dirac's theorem on cycles in k-connected graphs

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. ISBN 0-444-87129-2.