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

["Mark Boon" <tesuji@xxxxxxxxx>]

One of the things I was planning for a second version of this library was
including a pattern-matcher. Not the one that is in Goliath (it's fast but
too cluncky), but a much better one we had in the Tsume-Go program. I'm sure
every existing Go program has a pattern-matcher of some sort, and every
future Go program will need one.

To be honest though, I have no idea how my pattern-matcher compares in speed
with others. So my first question is what would be good metrics to compare
them?

Next what I want to bring up is of practical nature. Although a
pattern-matcher of stones is the essential core of a pattern-matcher, to be
really useful some other issues are involved. The first one is storage. In
the past I've always stored patterns in files, but it's actually very
cumbersome. Nowadays I'd store them in a database. The second issue is that
of something I call 'extra conditions' attached to patterns. Stone patterns
only get you so far, I need to be able to include information as 'this stone
is not in atari', or 'this point is a false eye'. Since the latter
information is very closely tied to the data structures of the Go program,
it's not easy to separate out the pattern-matcher from this
application-specific part.

The way these extra conditions are represented in my application is by a
simple string of the following form:
<letter-code><coordinate><operation-code><value> Some examples are: L3,2>1
or e4,5!0 which would mean something like: the stone at 3,2 has more than 1
liberties and the point at 4,5 is not eye-space.

Anyway, at the moment I have some spare time which I could put into making a
good pattern-matcher available. But there's little point if there's already
a public one available unless mine is substantially faster. So I'd need some
way to compare. Probably as important as the pattern-matcher itself is a
pattern-editor. Generally this takes more programming time than the matcher,
but here also the handling of the extra conditions make it not so clear how
to make something that is generally useful.

I'd be interested to hear some opinions and/or ideas on this.

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