# Gabriel Andrew Dirac

Gabriel Andrew Dirac (born March 13, 1925 in Budapest , † July 20, 1984 in Arlesheim ) was a Hungarian-British mathematician who dealt with graph theory.

Gabriel Dirac was the son of Eugene Paul Wigner's sister Margit from his first marriage. When she married Paul Dirac in 1937 , Gabriel and his sister Judith moved to England and also took the name Dirac (as well as British citizenship). During the Second World War he worked in the aircraft industry. Dirac studied at the University of Cambridge and the University of London , where he received his doctorate in 1951 under Richard Rado (On the Coloring of Graphs: Combinatorial topology of Linear Complexes). In the same year he received the Rayleigh Prize from Cambridge University. He then went to the Universities of London, Hamburg, Toronto, Dublin (Trinity College), Vienna, Ilmenau and Swansea. 1966/67 and from 1970 he was professor at the University of Aarhus .

Dirac was one of the leading graph theorists. In particular, he worked on graph coloring and, related to this, also on map coloring (and the four-color problem ). In 1952 he found a new necessary criterion for the existence of Hamilton paths in graphs. In the same year he proved the Hajós conjecture for (but in general it is wrong, as proved by Paul Catlin in 1979). He also dealt with number theory and geometry. ${\ displaystyle k \ leq 4}$

He had four children with his wife, Rosemari Dirac.

He was one of the editors of the Journal of Graph Theory and the European Journal of Combinatorics. In 1962 he gave a lecture at the International Congress of Mathematicians in Stockholm ( Remarks on the four color conjecture and the theory of graphs ).

## literature

• L. Døvling Anderson, I. Tafteberg Jakobsen, C. Thomassen, B. Toft, PD Vestergaard (editors): Graph theory in memory of Gabriel Dirac, Annals of Discrete Mathematics, Vol. 41, North Holland 1989
• Carsten Thomassen , Obituary in Journal of Graph Theory, Vol. 9, 1985, pp. 303-318

## Individual evidence

1. Anderson et al. a. Graph theory in memory of Dirac , Annals of Discrete Mathematics, 1989, p. 1