Er forschte über perfekte Graphen, Graphen-Minoren, Zufalls-Graphen, optimale Graphenfärbung unter Anwendung probabilistischer Methoden und Algorithmen zur Lösung von graphentheoretischen Problemen, die in Anwendungen wie Telefon-Netzwerken, VLSI-Design und dem World Wide Web anfallen.
mit Michael Molloy: Graph Colouring and the Probabilistic Method, Algorithms and Combinatorics 23, Berlin: Springer-Verlag 2002
mit Noga Alon, Colin McDiarmid: Acyclic coloring of graphs, Random Structures & Algorithms, Band 2, 1991, S. 277–288
mit V. Chvátal: Mick gets some (the odds are on his side), Proc. 33rd Annual Symposium on Foundations of Computer Science, 1992, S. 620–627.
Finding approximate separators and computing tree width quickly, Proc. 24th Annual ACM Symposium on Theory of computing, 1992, S. 221–228.
mit Michael Molloy: A critical point for random graphs with a given degree sequence, Random Structures & Algorithms, Band 6, 1995, S. 161–179.
Tree width and tangles: a new connectivity measure and some applications, Surveys in combinatorics, 1997 (London), London Math. Soc. Lecture Note Ser. 241, Cambridge: Cambridge Univ. Press, 1997, S. 87–162.
mit M. Molloy: The size of the giant component of a random graph with a given degree sequence, Combinatorics, Probability and Computing, Band 7, 1998, S. 295–305.
mit M. Molloy: Further algorithmic aspects of the local lemma, Proc. 30th Annual ACM Symposium on Theory of computing, 1998, S. 524–529.