Unusual seki
Ford Prefect
number of groups (>= 2), like the following (with 4 groups in the seki):
. . . . . . . . . . . . . .
. . . . . . . O O . . . . .
. . . . . . . O . O . . . .
. . . # # # # O O . O . . .
. . # . # O O # O O O . . .
. # . # # O . # # # O . . .
. # # # O O O # . # O . . .
. . . O # . # O O O # # # .
. . . O # # # . O # # . # .
. . . O O O # O O # . # . .
. . . O . O O # # # # . . .
. . . . O . O . . . . . . .
. . . . . O O . . . . . . .
. . . . . . . . . . . . . .
Along the lines of the "how many living groups" thread is the following
question: on a 19x19 board, what is the largest number of groups that
can be in seki at a time? (It's not hard to build a position, using
techniques like in the above, where every stone is part of a group in
seki and there are 48 of them.)
Really, this stuff will probably never happen in a real game of go, but
I got a kick out of realising that a proper definition of seki cannot
rely on the number of groups involved. Four-way seki is not so
unreasonable as it might appear, though. I think maybe there are
sensible invasions that could force such a beast into existance.
-- Ford
Rick Rubenstein
> Along the lines of the "how many living groups" thread is the following
> question: on a 19x19 board, what is the largest number of groups that
> can be in seki at a time? (It's not hard to build a position, using
> techniques like in the above, where every stone is part of a group in
> seki and there are 48 of them.)
This is interesting stuff. A great deal of work in recreational
mathematics has concerned "chess tasks", problems based on the board and
rules of chess but unrelated to ordinary game play (e.g., How many queens
can be placed on a chess board such that none attacks the other). I do not
know how much similar work has been done on "go tasks", but I have heard
of very little.
Here's a task suggested by the whole-board ladder problems in _The
Treasure Chest Enigma_: On a board of a given size, what's the maximum
number of moves that can be required to capture a stone in a ladder?
-Rick Rubenstein
dln...@imap2.asu.edu
: I discovered the other day that one can construct a seki involving an arbitrary
: number of groups (>= 2), like the following (with 4 groups in the seki):
: . . . . . . . . . . . . . .
: . . . . . . . O O . . . . .
: . . . . . . . O . O . . . .
: . . . # # # # O O . O . . .
: . . # . # O O # O O O . . .
: . # . # # O . # # # O . . .
: . # # # O O O # . # O . . .
: . . . O # . # O O O # # # .
: . . . O # # # . O # # . # .
: . . . O O O # O O # . # . .
: . . . O . O O # # # # . . .
: . . . . O . O . . . . . . .
: . . . . . O O . . . . . . .
: . . . . . . . . . . . . . .
: Along the lines of the "how many living groups" thread is the following
: question: on a 19x19 board, what is the largest number of groups that
: can be in seki at a time? (It's not hard to build a position, using
: techniques like in the above, where every stone is part of a group in
: seki and there are 48 of them.)
: Really, this stuff will probably never happen in a real game of go, but
: I got a kick out of realising that a proper definition of seki cannot
: rely on the number of groups involved. Four-way seki is not so
: unreasonable as it might appear, though. I think maybe there are
: sensible invasions that could force such a beast into existance.
: -- Ford
Although I have never seen a four-way seki, I have had a game with a three
group seki. The outer two groups had one eye each, and the inner group
shared one liberty with each outer group. My sensei said at the time that
he had never seen one like it. Unfortunatly, I didn't record the game to
see how it developed.
David Carper
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