kilobug comments on A fungibility theorem - Less Wrong

21 Post author: Nisan 12 January 2013 09:27AM

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Comment author: kilobug 13 January 2013 05:32:13PM -1 points [-]

Hum, yes, indeed I got the P and V_i backwards, sorry.

The argument still holds, but with the other inversion between the \forall and the \exists :

such as then if P is pareto optimal, then P is a maximum of .

Having an utility function means the weighting (the c_i) can vary between each individuals, but not between situations. If for each situation ("world history" more exactly) you chose a different set of coefficients, it's no longer an utility function - and you can make about anything with that, just choosing the coefficients you want.

Comment author: Vaniver 13 January 2013 05:54:21PM *  1 point [-]

That doesn't work, because is defined as a mapping from to the reals; if you change , then you also change , and so you can't define them out of order.

I suspect you're confusing , the individual policies that an agent could adopt, and , the complete collection of policies that the agent could adopt.

Another way to express the theorem is that there is a many-to-one mapping from choices of to Pareto optimal policies that maximize that choice of .

[Edit] It's not strictly many-to-one, since you can choose s that make you indifferent between multiple Pareto optimal basic policies, but you recapture the many-to-one behavior if you massage your definition of "policy," and it's many-to-one for most choices of .