I remember another way to estimate peak capabilities. This one was used in the 
late 1970's by Ken Thompson / Belle, but maybe was invented earlier: play 
handicap matches at different time controls, and fit a quadratic curve to the 
data. If your program is strong enough, then additional computational effort 
shows diminishing returns. If your program is too weak, then the performance 
scales linearly, and you don't see diminishing returns to higher computational 
effort.

It is also possible to have a peak that falls short of perfection if your 
program's algorithms are not asymptotically optimal, but that was not a problem 
for chess programs. Belle was 1100 rating points lower than current programs, 
and it already showed diminishing returns. I recall that the method gave 
reasonable results. E.g., I remember estimating that Belle would need at least 
depth 13 searches to contend for championship caliber.

-----Original Message-----
From: Brian Sheppard [mailto:sheppar...@aol.com] 
Sent: Tuesday, March 15, 2016 6:20 PM
To: 'computer-go@computer-go.org' <computer-go@computer-go.org>
Subject: RE: [Computer-go] AlphaGo & DCNN: Handling long-range dependency

>So a small error in the opening or middle game can literally be worth anything 
>by the time the game ends.

These are my estimates: human pros >= 24 points lost, and >= 5 game-losing 
errors against other human pros.

I relayed my experience of a comparable experiment with chess, and how those 
estimates proved to be loose lower bounds, and it would not surprise me if 
these estimates are also far from perfection.

I urge you to construct a model that you feel embodies important 
characteristics, and get back to us with your estimates.

-----Original Message-----
From: Computer-go [mailto:computer-go-boun...@computer-go.org] On Behalf Of 
Darren Cook
Sent: Monday, March 14, 2016 5:15 PM
To: computer-go@computer-go.org
Subject: Re: [Computer-go] AlphaGo & DCNN: Handling long-range dependency

> You can also look at the score differentials. If the game is perfect, 
> then the game ends up on 7 points every time. If players made one 
> small error (2 points), then the distribution would be much narrower 
> than it is.

I was with you up to this point, but players (computer and strong
humans) play to win, not to maximize the score. So a small error in the opening 
or middle game can literally be worth anything by the time the game ends.

> I am certain that there is a vast gap between humans and perfect play. 
> Maybe 24 points? Four stones??

24pts would be about two stones (if each handicap stone is twice komi, e.g. see 
http://senseis.xmp.net/?topic=2464).

The old saying is that a pro would need to take 3 to 4 stones against god (i.e. 
perfect play).

Darren
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