Chance Discovery and Scenario Analysis 1 Chance Discovery and Scenario Analysis Peter McBURNEY Department of Computer Science University of Liverpool Liverpool L69 7ZF UK Simon PARSONS Center for Co-ordination Science Sloan School of Management Massachusetts Institute of Technology Cambridge MA 02142 USA p.j.mcburney@csc.liv.ac.uk sparsons@mit.edu Received 26 February 2002 Abstract Scenario analysis is often used to identify possible chance events. However, no formal, computational theory yet exists for scenario analysis. In this paper, we commence development of such a theory by defining a scenario in an argumentation context, and by considering the question of when two scenarios are the same. Keywords Argumentation, Chance Discovery, Ensembles, Forecasting, Sce- narios. 1 Introduction The new discipline of chance discovery is concerned with the identification and management of rare, but significant, events, such as potential risks or opportunities,