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

David Fotland fotland at smart-games.com
Mon Mar 8 21:46:40 PST 2010

Many Faces still uses UCT to control exploration.


> -----Original Message-----
> From: computer-go-bounces at dvandva.org [mailto:computer-go-
> bounces at dvandva.org] On Behalf Of Petr Baudis
> Sent: Monday, March 08, 2010 12:30 PM
> To: Nick Wedd
> Cc: computer-go
> Subject: Re: [Computer-go] Congratulations to Many Faces of Go!
> 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
> details.
>   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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