Arnold is a lecturer in Economics at Queen's University Belfast. He holds a Master Degree from the University of Bielefeld and a Ph.D. in Economics from the University of Alicante. His research interests are mainly in socio-economic networks, bargaining theory,financial and computational economics but he occasionally ventures onto other ground. His current projects range from game-theoretical models of markets with repeated transactions through empirical work on socio-economic networks to the estimation of the value at risk. His recent publications include papers in Journal of Economic Theory and Journal of Industrial Economics.