Dear Hal At 1/18/02, you wrote:
snip >I'm not convinced about the models of computation involving GTMs and >such in Juergen Schmidhuber's paper. Basically these kinds of TMs can >change their mind about the output, and the machine doesn't know when >it is through changing its mind. So there is never any time you can >point to the output or even a prefix and say that part is done. It is >questionable to me whether this ought to count as computation. snip I am currently somewhat in accord with this view. My model of the ensemble of universes which is just approaching a "finished" condition is not a computational one. However, without regard to the application of "computation" to the comprehension of this ensemble I do not see an external difference between any of Juergen's machines and the usual UTM. Whenever a prefix is indeed done that is just the same as any external output of a UTM with the computation activity spread over a long section of tape internally IMO. snip As to the discussions of measure and probability re the likelihood of a particular sort of universe I do not see the point. The core idea for a founding postulate that seems most appealing is that no information exists. So the entire discussion re measure IMO is just an effort to extract a factual(s) from an ensemble of counterfactuals. Yours Hal Ruhl
