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Nisan comments on Problems of the Deutsch-Wallace version of Many Worlds - Less Wrong Discussion

4 Post author: Mitchell_Porter 16 December 2011 06:55AM

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Comment author: Nisan 17 December 2011 12:28:49AM 1 point [-]

Ah, I thought of a charitable interpretation of "there is a unique (up to affine transformations) utility function over the rewards". Given a preference ordering on sequences of rewards, there is a unique utility function on individual rewards that recovers that preference ordering. I believe this because if rewards are repeatable, the diachronicity hypothesis implies that any utility function on sequences of rewards must be additive. (We also need a hypothesis ruling out lexicographically-ordered preferences.)

Comment author: pragmatist 17 December 2011 12:43:11AM *  0 points [-]

You're right. Diachronic consistency is required to establish the uniqueness of the utility function. Also, Wallace does include continuity axioms that rule out lexically ordered preferences, but I left them out of my summary for the sake of simplicity.