The permanent location of this page is http://www.goban.demon.co.uk/go/bestiary/rule_challenge.html
These "beasts" will be dealt with differently, depending on which set of "rules" is used. By "rules", I mean not only those that have been officially adopted at some time, but also those that have been discussed and/or proposed.
I have written a somewhat sketchy paper called Multistage Kos : Zippers, Wheels, Loops, etc, in which I discuss some discoveries relating to very artificial situations.
In this collection, I have made little attempt to provide an explanation for each Diagram -- please check with the original article.
References to the publication "Go" are to the journal "Go" of the Nederlandse Go Bond, which published a sporadic Series entitled "Goochelrubriek" {Jaap K Blom tells me that Ger agreed that this is to be interpreted, in English, as "Weichicraft" -- 'Goochelen' is wizardry and a 'goochelaar' an illusionist}. As far as I know, all of these were written by Ger Hungerink. I am especially grateful to Theo van Ees, who took the trouble to find copies of the original journals, and send them to me.
Hans Mulder ( hans@icgned.nl) kindly sent me many useful comments on 18 October 1996. I have used, and slightly changed, his comments -- I mark these with "[HM]" -- all faults are my own.
If White can play at "A" then Black cannot kill White, otherwise White dies.
If Black has to capture at A19 (top left) then it will be easier for White to live than if White has commited suicide at A19. In either of these cases White is better off than in the Japanese Rules.
White to Play
White to Play
White to Play
White to Play
A very similar (? logically identical) position is discussed below.
Here's a message that I got from Nick Wedd ( Nick@maproom.demon.co.uk) on Fri, 23 Aug 1996.
Here is the position from the Journal of the Congres Europeen de Go, 1987
(lower edge of board)
. . . . . . . . . . . . . . . . . . .
. . . . . . . O O O O O O . . . . . .
. . . . . . O . . . . . . O . . . . .
. . O O O . O X X X X X X O . O O O .
. O . . . . O X . O O O X O . . . . .
. . X X X X X O O . . O O X X X X X .
^ ^ ^ ^
p q r s
Problem 1: Black to play and leave his group dead.
Answer 1: Black plays at "r".
Explanation: Eventually, White will fill in the outside liberties,
obliging Black to capture above "q". Whenever he does this, White throws
in at "p".
(lower edge of board)
. . . . . . . . . . . . . . . . . . .
. . . . . . . O O O O O O . . . . . .
. . . . . . O . . . . . . O . . . . .
. . O O O . O X X X X X X O . O O O .
. O . . . . O X . O O O X O . . . . .
. . X X X X X O O X . O O X X X X X .
^ ^ ^ ^
p q r s
Problem 2: Black to play and live.
Answer 2: Black plays at "s", removing two of his own stones (he need
not do this immediately).
Explanation: In the original diagram, Black was alive.
Bilateral Double Ko
Source: "the Structure of Go", Karl Davis Robinson and John M H Olmstead; unpublished Typescript, 1946
"On The Rules of Go" -- page 60 (sections 6.9 and 6.10), Ikeda Toshio (Translated, and augmented by James Davies), Published posthumously by Fujitsu Limited, Tokyo, 1992. Translations of articles that appeared in "Igo Shincho" between September 1968 and November 1969. [This is the best book I have found on the general theory of the Rules of Go -- available from "Crystalline Creations" ("ToyoGo", as was) HF]. There is now a WWW version of Ikeda Toshio's "On The Rules of Go".
At Left: "Unstable Seki": Thousand Year Ko -- Black plays at C1, and after the capture at C3, plays at B2 -- we then have W B1, B A2, W C2, B A1 for the Mannen ko. If Black captures and connects . . then Black can play another sacrifice, starting at A3 -- W captures at B3, B A2, W A2, B B1 to give Seki! [I just love this one -- HF]
There is a paper written in the mid-late 1990's in which this position is discussed from the point of view of Combinatorial Game Theory. I have forgotten the author, but believe that it was neither Elwyn Berlekamp, nor David Wolfe, though it was someone working with them (I think!). If you know who it was, and/or where to obtain a copy, please tell me -- thank you.
At Right: "Unstable Seki" : Ko -- B can start this with S1 . . .
"On The Rules of Go" -- page 62 (section 6.12) -- Ikeda Toshio (Translated, and augmented by James Davies). Based on "Igo No Suri" (on the Mathematics of Go) by Shimada Takuji, publ by Kawade Shobo in 1943 -- a revised edition published in 1958 by Maki Shoten. BLACK TO PLAY.
"On The Rules of Go" -- page 61 (section 6.11) -- Ikeda Toshio (Translated, and augmented by James Davies). "Unstable Seki: Capturing Half a Group". WHITE TO PLAY
from "Remarks on the Ing Rules" by Jan Rueten-Budde, Kiel in the "Ars Electronica Computer Go Tournament 1990" handbook, by Anton Steininger. This position is attributed to "a paper by V. Gourvitsh from the USSR"
This position gives a win by 1/420th of a point in some Ing Rules of the 1980s. Fractional points in seki are no longer in the Ing Rules!
QUESTION: On an infinite board is it possible to construct a seki in which two adjacent groups share 5 liberties? If yes, then what is the smallest board on which this is possible? [HM]. Please send answers to me (and/or to Hans Mulder).
[HF : I think that suicide plays a role here - can anyone explain this position?]
Many Thanks to Fred Hansen of the Andrew Consortium for the gifs which he created from files consisting of X's and O's, using their tools. Thanks also to Fred, Hans Mulder, and Nick Wedd, for pointing out several errors, and generally improving the quality of the annotations.
Last Updated 2001/02/21
This page maintained by Harry@goban.demon.co.uk.NOSPAM (sorry please remove ".NOSPAM" from my address), whose WWW page is Harry Fearnley's Home Page