On 05/08/2014 12:25, Erik van der Werf wrote:
Here's an intuitive argument for why I believe 7.5 komi is too high on
any of the larger boards.
On very small (square odd-surface) boards there is no room for White
to live (Black takes all points). Past a certain point (5x5), Black
can no longer control the full board, so White also starts to take
some points. Initially there is not much room left for White, so the
perfect komi remains a bit high (e.g., 9 for 7x7), but as the size
increases the White move values start to approach those of Black and I
expect the advantage of the initiative to decrease to a constant
(probably 7 or 5 points).
Since we have reasonable indications that the first player score on
9x9 is no higher than 7, and because it is unlikely to increase with
size, the main question is if it remains at 7, or if it drops down
further (e.g., to 5). (even values such as 6 are much less likely on
odd-surface boards with area scoring).
Of course one could still argue that 7 is correct, and we just add 0.5
to prevent ties, but then I'd rather subtract 0.5 and go for a komi
of 6.5 because I prefer the small advantage to go to the first player.
I find your logic convincing. We'll see if others do.
But even if they do, is that a sufficient reason for changing the komi
in events that I run?
With 9x9, getting the komi slightly wrong biases the results markedly,
and so should be avoided. With 19x19, getting the komi slightly wrong
makes much less difference to the results of games, and it may be better
to use slightly wrong komi than to inconvenience those bot
authors who have not persuaded their bots to understand integer komi
and the possibility of jigo.
Best,
Erik
BTW Nick, is there any chance that you will at some point run a kgs
tournament with territory scoring? I'm still hoping that one day we
will play Japanese rules with 6.5 komi. (Regardless of the komi, I
think the more fine-grained territory scores would make the games more
interesting, especially on 9x9.)
I use area scoring because, with the KGS clean-up procedure, it allows
almost all games to end without my intervention. KGS does not offer a
similar mechanism for what it calls "Japanese rules". I do not want
to be required to apply my rules knowledge and counting ability in a
game which ends with the players disputing the status of a "bent four
in the corner".
Nick
On Tue, Aug 5, 2014 at 11:10 AM, Nick Wedd <n...@maproom.co.uk> wrote:
In January 2011, I took a poll on what komi to use for 9x9 bot
tournaments on KGS. There was a majority in favour of changing from
7.5 to 7.
During Sunday's 13x13 KGS bot tour, someone suggested also changing
the 13x13 komi from 7.5 to 7. The main argument for changing must
be that 7.5 favours White. So here are the statistics from recent
KGS 13x13 bot tournaments:
White Black
wins wins
2014 August 13 9
April 36 27
2103 December 12 18
April 28 20
TOTALS 89 74
I am inclined to think there is not a convincing reason to change.
But I will welcome persuasion; or better, more statistics.
Nick
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Nick Wedd
n...@maproom.co.uk
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