Re: Value of a group

[David Mechner <mechner@xxxxxxxxxxxxxxxxx>]

> How about this way of judging cutting stone importance:
>  1.Pretend it has absolute life. What is the score?
>  2.Pretend it is dead. What is the score?
> 
> If a big difference it's important. Maybe this method could 
> be used to judge the value of any group? 

We calculate and keep track of a "liability" rating for each non-dead
group, which is essentially a point penalty for having a weak
(attackable) group that gets added into the territory count. The swing
that you describe is what we call the "raw" liability, which we then
weight by the strength of the group:
	Liability = RawLiability * (1-Strength) 
Where strength ranges from almost 0 (almost totally but not quite dead)
to 1 (perfectly alive). 

The value of a capturing a cutting stone is then calculated by finding
its effect on liability. 

> It sounds slow though!

Yeah.
 
> Finding the value of attacks on a group can maybe only be 
> done with search?

Yes - assuming you need search to do life & death. In general you can
hardly say anything worthwhile in go without life & death knowledge.

-David