Re: Korean Indirect Kos

[Robert Jasiek]

>>
The KBA 1992 Rules have the following precedental rule:

# O a . # O . . .
. # # # # O . . .
# # O O O O . . .
O O O . . . . . .
. . . . . . . . .

In [the figure], if Black clearly has [more ko-threats], Black a is not
needed.
<<

During the EGC I have asked several Korean professionals and strong
amateurs whether they could explain the rule to me. The (partially
implicit) replies were as follows, where some pros stated several of
them whenever I suggested some possibility:

1) Very frequent: "I do not know the Korean rules (well enough)." [1:
"But isn't 'common sense' good enough?"]

2) Rather frequent: "I do not know that particular rule. The general
play-everything-out rule applies." [1: "But I know how the Japanese
rules apply to that position."]

3) 2 or 3, when already being suggested this answer: "A ko threat can be
of any (small) size. I have not considered whether a pass might be a ko
threat."

4) 1 or 2, when already being suggested this answer: "A ko threat has to
be at least as big as the ko. I do not know the exact size of the ko."

5) 1, when already being suggested this answer: "A ko threat has to have
a [deiri] size of at least 20 (i.e. 20 rather than 21)."

6) 1, his own opinion: "Having more ko threats means: being
[hypothetically in continued alternation] able to win [or otherwise
avoid losing?!] the game by not playing Black a. I do not know any
details about passes, multiples, or colour-reversed multiples."

7) 2 as an additional opinion when pressed hard for an answer: "The rule
applies only if the outer [white] stones are [J2003-uncapturable and
surround the inner stones tightly]."

8) Rather frequent: "I do not (sufficiently exactly) know what an
indirect ko / a ko with approach moves is. In particular, I do not know
whether the rule applies to such kos only."

Conclusions:
- Judging empirically, by far the most strong Korean players do not know
the KBA 1992 Rules well.
- There are too many different opinions by strong Korean players about
application of the KBA 1992 Rules.
- The IMO most convincing answer would be a combination of (6), (7), and
the opposite of (8)...

--
robert jasiek