Re: [computer-go] Pattern Matcher (was M.Boon-Library)

[Daniel Bump <bump@xxxxxxxxxxxxxxxxxx>]

Mark Boon wrote:

> First of all I find your patterns very hard to read. Maybe this gets better
> with a good editor?

It gets better with practice. I think the editor is irrelevant
since the patterns are written in ascii.

> I've heard about others using the '(opponents) stone or empty' but I find it
> rarely useful. Although technically it happens that two patterns are the
> same except for a position where there could be a stone or empty, as a Go
> player I find that they are so inherently different that I would make an
> extra pattern. Would it add more than a few percent in the number of
> patterns in your case?

It's hugely useful. Browse the GNU Go patterns and see how
often o and x occur.

> What I miss is the opponents move. Generally patterns are such that either
> player could be to move.

I'm not sure what you mean by the second sentence. You might be
expressing the proverb `my enemy's vital point is my vital point,'
or you might be just saying you can't tell who's to move in the
patterns.

O is always the player to move, X is the opponent, and * is the
location of the move. A few patterns are duplicated with the O's
and X's reverse, especially in the owl patterns.

> Generating C-code is not going to work for me, although it probably could
> just as easily be generating Java code. But the real question is: how does
> it perform? My pattern-matcher takes all the patterns in a set and (tries
> to) constructs an optimal decision-tree to match the patterns in the least
> number of steps. I wonder if by generating C-code you can reach the same
> kind of optimization. I suppose in principle it should be possible, but it
> seems so much more difficult to me. Or maybe it comes down to roughly the
> same thing?

The purpose of the DFA sounds similar to the decision tree you
describe. The purpose of the C code in GNU Go's constraints is
very general. For example you can call the reading code and
ask if after several stones are played whether something can
be captured.

GNU Go documentation on the web has just been revised:

http://www.gnu.org/software/gnugo/gnugo_toc.html

The pattern matcher is described in quite a bit of
detail here:

http://www.gnu.org/software/gnugo/gnugo_9.html#SEC108

Dan
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