I. M. Flaud quotes extended passages from a later edition of von Neumann and Morgenstern dealing with the extension of the notion of a zero-sum game to n-person games, n greater than 2. This is totally new to me and I need to hunt that up and look at it before I try to respond.
One question to I. M. Flaud: Whom are you quoting? von Neumann died in '57, I think, and a 60th anniversary edition would have appeared in 2004. The language quoted about gains and losses makes it sound as though we are talking not about zero sums of utility but zero sums of money, which are of course interpersonally comparable. So that is an entirely different question.
Can you throw any light on this?