Crispin Nash-Williams

Crispin St John Alvah Nash-Williams FRSE (19 December 1932 – 20 January 2001) was a British mathematician. His research interest was in the field of discrete mathematics, especially graph theory.

Biography Nash-Williams was born on 19 December 1932 in Cardiff, Wales. His father, Victor Erle Nash-Williams ( Williams), was an archaeologist at University College Cardiff, and his mother had studied classics at Oxford. As a small boy, Nash-Williams attended Christ Church Cathedral School in Oxford, which was then headed by Wilfrid Oldaker. A biographer has said that Oldaker was a formative influence on Nash-Williams. He then attended Rugby School until the age of 18. writes that "Themes running through his papers are Hamiltonian cycles, Eulerian graphs, spanning trees, the marriage problem, detachments, reconstruction, and infinite graphs." In his first papers Nash-Williams considered the knight's tour and random walk problems on infinite graphs; the latter paper included an important recurrence criterion for general Markov chains, and was also the first to apply electrical network techniques of Rayleigh to random walks. His dissertation, which he finished in 1958, concerned generalizations of Euler tours to infinite graphs.

Welsh writes that his subsequent work defining and characterizing the arboricity of graphs (discovered in parallel and independently by W. T. Tutte) has "had a huge impact," in part because of its implications in matroid theory. Nash-Williams also studied k-edge-connected graphs, Hamiltonian cycles in dense graphs, versions of the reconstruction conjecture for infinite graphs, and the theory of quasi-orders. He also gave a short elegant proof of Kruskal's tree theorem.