Thanks for all these responses and discussions here! I'd like to try to gather 
pieces in this thread so far and to make the consensuses more clear to me (and 
others hopefully).

Consensus 1: given the searching/playout policies, more playouts will GENERALLY 
contribute to a stronger program.

Here the term "generally" means that the observations are from statistics (or 
the sense we got empirically) upon large number of games between various GO 
bots, rather than refering to any specific cases/situations. So an 
example-based arguement is not valid here.

However, two questions for this consensus:

(1.a) Inhttp://cgos.boardspace.net/study/, the ELO improvement from doubling 
the number of playouts seems converge to 3000 score. Is this because versions 
with 3000+ ELO is "too strong" to be measured accurately? More importantly, 
seems these results are self-playing game records, which is known to have 
amplification effect on the ELO score improvement.

(1.b) Generally speaking, we always want the progam to "show its best" in an 
important tournament like Olympaid, and assuming the consensus, more playouts 
will always helps this. As a consequence, there should be no serious player for 
the Olympaid who run their program on laptop (unless they are fully confident 
that the capability of their program shown in laptop is *already* strong enough 
to beat all others!). Note that "the authors prefer the algorithm-part 
improvement" or "software algorithm just matters much more" do not answer this 
question, since no matter what algorithmic improvement here, we just assume 
that more playouts give orthogonal contributions, right?

Consensus 2: there is a trade-off between the quality of playout and the speed 
of playout.

it's very interesting for me to find that consensus 2 actually has little 
necessary relation with consensus 1. First, the speed of playout translates to 
the number of playout only under fixed computation resources. So even the 
playout becomes slow due to a more complex playout policy, we can achieve the 
same number of playouts by simply using more CPU cores. Second, even though we 
do have the "quality vs number" trade-off given fixed CPU cores, this does not 
conflict with the fact that "number" brings additional contributions for given 
"quality".

But seems all strong programs just favor the "quality" in this trade-off, 
because more playouts tend to make the same errors with previous playouts so 
they can hardly recover these errors in reasonable time. On the other hand, 
everyone admit that the random playout is clearly out of the sweet spot area of 
this trade-off.

Finally, I'm trying to find a "lower bound quality" for any meaningful 
trade-off, but there seems no convincing answer.

Bojun 

 
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