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[gnugo-devel] Fwd: [computer-go] April KGS on-line computer Go tournamen

From: David G Doshay
Subject: [gnugo-devel] Fwd: [computer-go] April KGS on-line computer Go tournament
Date: Wed, 3 May 2006 12:32:57 -0700

Begin forwarded message:
The fourteenth KGS computer Go tournament will be this Sunday, May 7th, in the European evening, American morning, and Asian night.

The Formal division will be on 13x13 boards, the Open division on 9x9 boards. Both will use fast time limits, 13 minutes each sudden death and 8 minutes each sudden death respectively.

Hello GNU Go folks,

I would like to enter SlugGo in this tournament, and would like to know which of the divisions, if either or both, the GNU Go team prefers for itself. I will have enough CPUs to enter both, but the rules stipulate that I can only be in the Formal division with your permission. I think it best to apply the same logic to both divisions because of the way that SlugGo uses the GNU Go engine. That is to say, I will also only enter the Open division with your permission. Of course, a SlugGo win against GNU Go is not guaranteed, the cgos results show that SlugGo_l3 has about a 61% win rate over the ggexp versions, 71% over 3.7.4, and 83% against 3.6 (the version we are presently using) on 9x9.

We have not done any tests at all with SlugGo on 13x13, but are curious about how well we would do. There have been enough surprises on 9x9 that we have no basis for guessing how those results will scale to 13.

To be specific, SlugGo_l3 does 12 way branching at the top level, and then linear lookahead 3 more levels. SlugGo_88 does 8 way branching at each of the top 2 levels (64 CPUs doing lookahead) with the same maximum depth, and does slightly worse against almost all strong opponents, but most notable is the fact that the advantage l3 shows against GNU Go is completely erased. While this at first confused us, we came to realize that this is because with second-level branching SlugGo evaluated the mistakes that GNU Go would make as unlikely to happen because other choices were considered to be better, whereas with l3 GNU Go's mistakes were taken as the only likely response and thus were accepted and taken advantage of. It is not clear why 88 played slightly weaker against other programs, where we had expected that the additional move choices might give us a better evaluation of a number of possible responses. But it is clear that the primary reason that the cgos ELO score of l3 is higher than that of 88 is that l3 takes proper advantage of GNU Go mistakes, while 88 out- thinks itself and rates those mistakes as unlikely. SlugGo_88 uses the same evaluation function for choosing the first level 8 choices as for the second level 8, and it is not clear to us why an evaluation function that shows some improvement when applied at the top level would be weaker against non-GNU Go opponents when applied to their possible responses. This is something we will investigate "soon."

But I digress ...

I would be happy to enter SlugGo in both divisions, but will accept the GNU Go team's decision with respect to each division.


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