Re: [gnugo-devel] reverse followup valuation

[Arend Bayer]

On Tue, 12 Aug 2003, Paul Pogonyshev wrote:

> i have recently spotted quite a few positions where reverse
> followup is completely inadequate.  here are two very common
> cases:
>
>       XXXX
>       XO.O
>       XO.O
>       XXXX
>
> in this position the moves at '.' are avarded large reverse
> followups because they prevent an atari.  i can see no way to

I don't see any problem with this. A 0 pt move with large
reverse followup value is still a 0 pt move. If not, the move valuation
is broken.

Evan has already pointed out where this reverse followup value is
actually needed.

> second common position is like this:
>
> OXXXXX
> .OO*..
> ------
>
> the move at '*' is avarded a reverse followup because it
> "prevents" atari.  actually, it only prevents atari from

Here, too, I think we need the reverse followup value. This move should
be valued 1pt territorial value, + >=3 pts reverse followup value
=> 2pts total value, which is correct here. (The point is that an X move
at * is sente. The reverse followup value does not say anything about
the O move being sente or gote.)

(2pts means this move is worth exactly as much as

OOOOXXXXX
...O*OX..
---------
)


Arend