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

[Joel Uckelman <uckelman@xxxxxxxxxxx>]

Quoth =?iso-8859-1?Q?J=F6rg_Rathlev?=:
> 
> >=20
> > http://www.yutopian.com/go/goLes/goLes1.html
> >=20
> 
> Ok, I have one question regarding Lesson 5, in the upper right corner, =
> where the board looks like this:
> 
>  . o # a # b
>  . o # # # #
>  . . o o o o
>  . . . . . .
> 
> (o is white, # is black)
> 
> The text says that white can't play simultaneously at a and b, therefore =
> black is alive. Could white play at one of these positions, or is it =
> impossible because then the white stone would be captured?
> 
> 
> Joerg

Nope. White can play at neither a nor b, because there is a prohibition on 
placing a stone where it would have no liberties, unless doing so would 
deprive enemy stones of all their liberties. In the case above, white can't 
play at a because the black dragon would still have one liberty, but white 
can't play at b for the same reason. So, the black stones are perfectly 
safe so long as the black player refrains from doing something dumb, e.g., 
filling in a or b.

-- 
J.