Lumifer comments on Rationality Quotes September 2014 - Less Wrong

8 Post author: jaime2000 03 September 2014 09:36PM

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Comment author: Lumifer 08 September 2014 01:39:18AM 1 point [-]

the utility function is, as a concept, defined to include everything; it is the function that takes world-states and determines how much you value that world.

Some utility functions value world-states. But it's also quite common to call a "utility function" something that shows/tells/calculates how much you value something specific.

The utility function is generally considered to map to the real numbers

I am not sure of that. Utility functions often map to ranks, for example.

Comment author: VAuroch 09 September 2014 07:00:23AM 0 points [-]

But it's also quite common to call a "utility function" something that shows/tells/calculates how much you value something specific.

I'm not familiar with that usage, Could you point me to a case in which the term was used, that way? Naively, if I saw that phrasing I would most likely consider it akin to a mathematical "abuse of notation", where it actually referred to "the utility of the world in which <X> exists over the otherwise-identical world in which <X> did not exist", but where the subtleties are not relevant to the example at hand and are taken as understood.

I am not sure of that. Utility functions often map to ranks, for example.

Could you provide an example of this also? In the cases where someone specifies the output of a utility function, I've always seen it be real or rational numbers. (Intuitively worldstates should be finite, like the universe, and therefore map to the rationals rather than reals, but this isn't important.)

Comment author: Lumifer 09 September 2014 06:45:16PM 0 points [-]

Could you point me to a case in which the term was used, that way?

Um, Wikipedia?

Comment author: VAuroch 09 September 2014 07:43:42PM 0 points [-]

That's an example of the rank ordering, but not of the first thing I asked for.

Comment author: Lumifer 09 September 2014 07:50:24PM 0 points [-]

The entire concept of utility in Wikipedia is the utility of specific goods, not of world-states.