Re: spoon-discuss: Re: spoon-business: Go move

[Benjamin Bradley <activist@xxxxxxxxxxxxx>]

On Fri, 30 Mar 2001, Joel Uckelman wrote:
> Quoth Jeff Schroeder:
> > Question about Rule 368/0 number 1. "Stones may not be placed so as to
> > repeat a previous Board configuration"  to what extent is this valid?  Is
> > this between different games?  Who defines the previous Board configuration?
>
> I meant this to be taken to apply only within games, not across them. As
> for its meaning, it means just that: if your proposed play would return the
> Board to precisely some Stone arrangement that has already occurred, then
> it's illegal. Don't worry, this sort of thing is only likely to happen on
> the very small scale. Once the game gets going, it should be almost
> impossible to return the board to a far earlier state.
>

more importantly, this is called "ko formation" and most often happens as
follows:
. . c b . .
. c _ c b .
. . c b . .
It is B's turn. B can play at _ because e will capture C and gain a
liberty, as follows:
. . c b . .
. c b _ b .
. . c b . .
Now C might want to play at _ to repeat the move, with sides reversed, but
since it would repeat a previous board configuration, it is an illegal
move. If there are intervening moves:
. c c b . .
. c b _ b b
. . c b . .
then it is now legal for C to play at _.


- Benjamin Bradley - "peaks and valleys"
- http://lostpoet.tripod.com/
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