The relationship between extensive and normal form analyses in non-cooperative game theory seems to be dominated, at least traditionally, by the so-called ‘sufficiency of the normal form principle’, according to which all that is necessary to analyse and ‘solve’ an extensive game is already in its normal form representation. The traditional defence of the sufficiency principle, that Myerson (1991, p. 50) attributes to von Neumann and Morgenstern, holds that, with respect to extensive games, it can be assumed without loss of generality, that players formulate simultaneously and independently their strategic plans at the beginning of the game – a situation which, it is claimed, is exactly described by the normal representation of an extensive game.