[Computer-go] Congratulations to Many Faces of Go!

Petr Baudis pasky at ucw.cz
Mon Mar 8 12:29:53 PST 2010

On Mon, Mar 08, 2010 at 04:43:29PM +0000, Nick Wedd wrote:
> Congratulations to Many Faces of Go, the undefeated winner of
> yesterday's KGS bot tournament.
> My report is at http://www.weddslist.com/kgs/past/57/index.html
> I hope you will report any errors, as usual.

  Thank you for the report!

  On the hardware - Puego was r1098, still run on the i7 920, but this
time with 8 threads instead of 4. CzechBot was still run on the same
hardware. pachi2 was AFAIK running on 21 cores, but probably not of
three Mac Pro machines - I hope Jean-Loup will be able to fill on the

  I beg to disagree with the analysis of the pachi2-ManyFaces1 game.
I think that the move at 177 was neccessary, there does not seem to be
alternative for white to live with its roup. Also, pachi2 kept being
very optimistic for the rest of the game and I also had the feeling
that the game looks favorable for white (though I did not count).
It seems to me that the blunder was only at the D19 move (267);
leaving the ko seems to be too dangerous and the bottom corner is not
enough compensation, especially given black's nasty followups. IMHO
the bot did not read the E19 ko correctly; I do not have detailed
winrate logs (yet?), though.

  Thank you for the praise of Pachi. :-) I'm sorry I confused you
on KGS previously, the bug was not in the codebase that was used
in the tournament. It does seem our flaw indeed is time management,
though in normal byoyomi games its clever implementation by jlg
boosts the strength - the problem seems to be poor handling of S.D.
and S.D.-like settings, probably due to faulty changes of mine.

  The surprise of the tournament for me was the excellent stv's
performance, looks like Steenvreter is to be reckoned with - I wonder
if its author plans to divulge more details on its internal operation.

  Finally, a general note on the UCT idea conclusion - I would say that
while the UCT is evolutionary at the beginning of current bots, the
current RAVE-based MCTS algorithm actually has nothing to do with UCT
anymore since the upper confidence bounds are not used anymore - the
RAVE information fully substitutes them as online exploration bias.
Perhaps "RAVET" instead of "UCT".  ;-)

  P.S.: I wish I would name Pachi's key component 'mcts' instead of
'uct' now. :-)

				Petr "Pasky" Baudis
http://pasky.or.cz/ | "Ars longa, vita brevis." -- Hippocrates

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