So8res comments on New paper from MIRI: "Toward idealized decision theory" - Less Wrong

27 Post author: So8res 16 December 2014 10:27PM

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Comment author: Skeptityke 21 December 2014 12:19:20AM 1 point [-]

I had an idea, and was wondering what its fatal flaw was. For UDT, what happens if, instead of proving theorems of the form "actionx --> utilityx" , it proves theorems of the form "PA+actionx |- utilityx"?

At a first glance, this seems to remove the problem of spurious counterfactuals implying any utility value, but there's probably something big I'm missing.

Comment author: So8res 21 December 2014 01:04:43AM 1 point [-]

PA + "A() = x" may be inconsistent (proving, e.g., that 0=1 etc.).

Comment author: Skeptityke 21 December 2014 01:27:35AM 1 point [-]

What happens if it only considers the action if it both failed to find "PA+A()=x" inconsistent and found a proof that PA+A()=x proves U()=x? Do an inconsistency check first and only consider/compare the action if the inconsistency check fails.

Comment author: So8res 21 December 2014 01:46:47AM 2 points [-]

Then you get spurious proofs of inconsistency :-)

(If PA is strong enough to prove what the agent will do, then PA + "A()=x" is only consistent for one particular action x, and the specific action x for which it is consistent will be up for grabs, depending upon which proof the inconsistency checker finds.)

Comment author: Skeptityke 21 December 2014 02:02:40AM 1 point [-]

Got it. Thank you!