Territory & dead stones?
- While the SGF standard mailing list is sort of active, let me first say
that I agree with Robert Jasiek in that a lot of things should be put in
general comments. IMHO, most properties are for
machine-readable-and-understandable data; the comments are for things
that humans are meant to read and understand. "Played during the Qing
dynasty" sounds like something you would never expect a computer to
understand, only a human, so it belongs in a comment.
Now for my problem. When a game is over, you need to mark dead stones
and territory. I believe that programs usually mark territory with TW
and TB, and mark dead stones by placing a TB/TW marker over them
(since usually a dead stone is in the territory of the opponent). But
there is one case I can think of where you have dead stones that are
*not* territory, and that's in an eye of a group in seki in Japanese
6 | O O O # # # #
7 | # # # O O O #
8 | # . # O . O #
9 | # O # . O O #
A B C D E F G H
Note the stone at B9. According to Japanese rules, it is dead and thus
worth one point to Black at the end of the game. But it
IS NOT TERRITORY. If it were marked with "TB", then Black would get
two points - one for the dead stone, and one for the point of territory.
This would be wrong. This wouldn't matter too much, but cgoban does
recognize seki and scores it correctly. It just doesn't know how to save
the scored poisition to an SGF file, so at the moment it (incorrectly)
labels the dead stone as territory.
So how do we mark this situation? Or does this fall into the
"it's-so-rare-that-who-cares" category? Seem to me that it would have
been nice to have a "DE" parameter to mark dead stones separate from
the TB/TW parameters, but it may be too late to add something like this
Bill Shubert (wms@...)
> Now for my problem. When a game is over, you need to mark dead stonesWhat one really needs to mark are the scoring points on the board.
> and territory.
If one liked to mark other things, one would have to use several
stages of diagrams. E.g. with the Nihon Kiin 1989 rules and at the
game end one might illustrate in the following order:
1 - living stones (distinguished: uncapturable stones, capturable stones
[but what about stones that are alive _and_ dead in case of incomplete
and incorrect play?]), dead stones, eye points, dame (all distinguished)
2 - stones of groups not in seki, stones of groups in seki, [optionally
any remaining stones], points of territory (all distinguished)
Not to mention extra troubles during the confirmation phase.
AYCS, rules intricacies are not useful for SGF properties. One
can still illustrate them by using labels, e.g. Stage 2 as above
might be shown with N, S, T labels (for stones of groups not in seki,
stones of groups in seki, points of territory). Or you offer three
diagrams for these.
> I believe that programs usually mark territory with TWWith some rule sets this can be reasonable. With most Japanese rule
> and TB, and mark dead stones by placing a TB/TW marker over them
> (since usually a dead stone is in the territory of the opponent).
sets it is not.
> there is one case I can think of where you have dead stones that areCorrect play would use the proper [encore] method of the exact Japanese
> *not* territory, and that's in an eye of a group in seki in Japanese
rule set to capture the dead stone(s).
> According to Japanese rules, it is dead and thusIt is only worth one point if being removed BEFORE the [completion of
> worth one point to Black at the end of the game.
end of the game. Otherwise it remains within a group in seki, where
is no territory from which stones would be allowed to be removed.
> If it were marked with "TB"With Japanese rules a mistake.
> This wouldn't matter too much, but cgoban doesSee above.
> recognize seki and scores it correctly.
> It just doesn't know how to saveIf you want to store the scored board points as well, you must not
> the scored poisition to an SGF file, so at the moment it (incorrectly)
> labels the dead stone as territory.
include any seki points (under Japanese rules). If the game ended as
shown, then the dead stone in seki does not belong to territory,
is not marked, and does not score at all.
> So how do we mark this situation?Do not mark it. Players should have played it out correctly.