[Computer-go] issues on 19x19

David Fotland fotland at smart-games.com
Thu Apr 28 11:25:49 PDT 2011


It looks like Crazystone/Bonobot is currently the strongest bot, and I think
it does not use rave, so rave is not essential for 19x19 go.

David

> -----Original Message-----
> From: computer-go-bounces at dvandva.org [mailto:computer-go-
> bounces at dvandva.org] On Behalf Of Petr Baudis
> Sent: Wednesday, April 27, 2011 11:11 AM
> To: computer-go at dvandva.org
> Subject: Re: [Computer-go] issues on 19x19
> 
>   Hi!
> 
> On Wed, Apr 27, 2011 at 11:23:41AM -0400, Daniel Shawul wrote:
> > 2) My second problem concerns use of progressive widening/unpruning
> which
> > looks like a must to have on 19x19.
> > The problem I have is with the move ordering... If I tell it to
> moves on
> > the 3rd line from the edge are good ones,
> > it continually puts its stones on that line (hence forming a square),
> while
> > the opponent controls the centre and also
> > cuts some parts of the 3rd line.
> > Then I used fillboard to try and fix this issue, but the engine once
> again
> > tends to prefer these moves and put stones
> > all over the board. Which is when I realized it is impossible to fix
> it with
> > static move ordering.
> > Should I use something dynamic like RAVE to order the moves? That
> will be
> > inconvinient  because I order the nodes
> > only during first allocation.
> > Also the default progressive unpruning formula seems to select too
> few moves
> > for consideration, so I had to add 20 additional moves
> > to make it work for my engine.
> 
>   You should explain in more detail exactly what you are doing right
> now, as the terminology is highly muddled. I assume that now, in n-th
> tree descent through given node, you consider only f(n) children for
> next move instead of all children. Also, I assume you use just plain
> UCT
> for node evaluation?
> 
>   I think progressive bias (considering all children, but giving extra
> bonuses to values of some or all children) is much better explored
> approach (at least in literature). However, it's certain that just
> using
> a single criterion for the ordering is not going to work well. You can
> either use a mix of patterns, hints from some other engine, or (best)
> RAVE values. Plus some extra coefficients for tactical checks (e.g.
> atari), last move CFG-distance and distance from edge.
> 
>   I think you will find it very difficult to achieve reasonable
> performance on 19x19 without RAVE. But if you are reluctant to do that
> yet, at least try combining last move CFG-distance, distance from edge,
> basic tactics and Mogo 3x3 patterns. The larger the mix, the more
> diverse your array of considered moves will be. In particular, I have
> found last move CFG-distance to be immensely important for gaining
> strength on 19x19.
> 
> --
> 				Petr "Pasky" Baudis
> UNIX is user friendly, it's just picky about who its friends are.
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