[computer-go] Opponent's suicidal moves can't be good

[alain Baeckeroot]

Le mercredi 30 août 2006 18:46, Francois Grieu a écrit :
> >>Under AGA rules, (or any rule set that forbids suicide
> >>and has the equivalent of pass stones), passing
> >>is equivalent, or better, to playing at an empty
> >>location where the suicide rule prevents the opponent
> >>from playing (given the board position, disregarding
> >>history of moves).
> >>By "equivalent, or better" it is meant the effect
> >>on the final score, assuming perfect play thereafter.
> 
> 
> >If I'm reading this correctly, it's not true. This would preclude 
> >filling false eyes, which is sometimes necessary. For example:
> >
> >w.wwB
> >.wwB.
> >wwwwB
> >BBBB. <-- black should play here, even though white cannot
> >.B.BB
> 
> My proposition works in this situation: Black can defer filling
> this false eye until W is allowed to play at the indicated spot,
> that is, after W has captured the two top B stones.
> 
> If there is a counterexample, I guess it must involve a ko.
> 
>    François Grieu

One simple counter example without ko, on the lower border:
XXXXX
XaOOX.
XObOX.
------

White O must play at 'b' and kill all black X
else
black X play at 'a' and is alive, even with suicide allowed.

Alain