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Re: [gnugo-devel] Three stone games

From: Morten Gulbrandsen
Subject: Re: [gnugo-devel] Three stone games
Date: Tue, 02 Apr 2002 16:25:34 +0200

Gunnar Farneback wrote:
> Morten wrote:
> > I expect the difference of one increased Handicap stone to be linear.
> Don't rely too much on that assumption. Especially not for huge
> handicaps.
> > I also find it very difficult to understand, why gnugo does not
> > increase its strength with computing speed? If gnugo plays against
> > itself with different time limits, then how many minutes will it
> > need to play 1 kyu stronger ?
> In principle it's possible to design a go program so that it will
> asymptotically play perfectly given a huge amount of time (and
> possibly memory), simply by doing a deeper and deeper global search.
> This has very limited practical applicability though, because static
> evaluation of the board is only trivial at the very end of the search
> tree (which is later than people usually stop playing). For all
> reasonable search depths, the static evaluation is extremely
> difficult and moreover very sensitive to any misevaluations of group
> status, connectivity, and so on.
> As it happens many programs, including GNU Go, don't bother with
> global search at all. It does quite a lot of local search though. The
> depth limits involved in these can certainly be increased if more time
> is allowed, but this only helps to a limited extent because:
> 1. Even with correct results of all local searches being done, the
> move selection depends on many heuristics which aren't helped by more
> available time.
> 2. The local searches are quite narrow with various heuristics to
> select moves. In order to maximally benefit from huge amounts of time,
> these would need to be modified as well, not only the explicit depth
> limits.
> To summarize this discussion, GNU Go and probably most other go
> programs as well, are not designed in a way which automatically makes
> them stronger just by giving them more time or faster hardware, at
> least not beyond some limit. It is certainly possible, and probably
> not even hard, to make modifications which would make GNU Go play
> substantially stronger if it was, say, allowed one week per move on a
> fast computer. The problem is just that those changes would require
> a significant amount of testing and tuning, which is simply
> infeasible.
> > When I started to play go, a korean 3-dan ranked player gave me 9
> > handicap stones, on a 9 x 9 board. Guess who won ? I had beaten a
> > korean nearly professional. And I was proud. Later he gave me 27
> > Handicap stones on a 19 x 19 board. If we cannot on any board size
> > with infinitely many handicap stones, like this:
> It's simple to arrange e.g. 136 handicap stones so that the opponent
> can't get a single alive stone even if the computer passes for the
> rest of the game.
> > please let a 9 dan professional try to play against this Handicap level
> > ?
> If you have the contacts and resources required to have a 9 dan
> professional play GNU Go you're welcome. We'll be most interested in
> any results.
> > I believe that even only 64 Handicap stones, would firmly beat most
> > drunk shodans, even in nearly total darkness, within 10 minutes, but
> > that could give us the reliable feedback, that if we could achieve
> > 50 % with 64 Handicap stones against 100 different 1-dan amateur
> > players, each playing 10 games, then gnugo has finally reached the
> > level of 64 Kyu. Which is my assumption.
> >
> > If this is the true, we have to confess it.
> > I believe it is a reliable way to find out the real-life strength.
> Not at all. I don't think it's hard to tune GNU Go to make it
> virtually unbeatable with some 30 or so handicap stones, but it would
> have absolutely no bearing on its playing ability in even games or
> with reasonable handicaps. And frankly, it would be a total waste of
> time.
It's my own time, I think this could be interesting for me.
According to the book Mathematical go 

Mathematical Go: Chilling Gets the Last Point 
Elwyn Berlekamp and David Wolfe

in late endgames even professional go moves can be improved by the 
algorithm presented in the book. It claimes to play better endgames than 

Has anyone purchased the software presented ?


> > And then we could try to increase the strength with decreasing 1
> > Handicap stone, every 3-6 month or so.
> If you think this is a good strategy to get a strong program, I'm
> afraid you don't know what you're talking about.
Well what I hope to achieve is some kind of 
evidence for worst case performance.

quicksort (Hoare) has a best case performance, average performance
and a well documented worst case performance. 

it is nothing to be ashamed of that gnu go has a worst case performance 
of say 30, 40, or 80 Kyu, as long as some of us are willing to work on
this and 
warn you for introducing improved go versions, with improved best case
and no one cares of investigating the worst case performance.

I am talking about improving go, and respecting you for your tremendous
average performance could be defined as some statistical measurement 
of gnugo versus HandTalk, ManyFaces Go4++  and the ten 'best' software
of go playing computers. If we have some definition of 'good' go playing

Best case performance could be defined as gnugo versus some complete
How many handicap stones do an average human need, with no experience in
If this can be to the promotion of go, gnugo has a mission. regardless
of its kyu strength.

Worst case performance I'd like to define ho many Handicap stones does
gnugo at least need,
in order to be completely unbeatable. by humans dan players,
professionals and by 
other software. 

If we don't know what we are talking about, how can we expect to code it

Yours Sincerely

Morten Gulbrandsen

> > It is no real achievement to play against ManyFaces or Handtalk,
> > when they perform moves lightyears apart from go moves played by
> > experienced dan ranked go players.
> >
> > We do want to beat a professional human, not ManyFaces or Handtalk ?
> In the short term it's very interesting to beat Many Faces or
> Handtalk, yes. To reach the top of the go programs would be a major
> achievement with significant publicity value. And it's infinitely more
> interesting than to beat professionals with 30 handicap stones.
> Notice that we also do lots of tuning on games against humans, mostly
> ones played on NNGS. There GNU Go is rated 13 kyu, which I think is a
> quite reasonable estimate of its real-life strength.
> /Gunnar
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