Re: Using partial plys

[David Mechner <mechner@xxxxxxxxxxx>]

Darren Cook wrote:
> Or could you just add a bonus to the evaluation function 
> for the side that has sente. If so, isn't calculating 
> the worth of sente going to be very inexact?

Wouldn't this be relative? If you're comparing the error of the sente
estimate to the error of the full-board static evaluation then (unless
you've had a breakthrough) it will probably be similarly exact, i.e.
decent in simple positions and terrible in complicated positions.

The way our program counts, which is modeled after the traditional human
method, is that it tries to calculate the size of each "area"
independently as the swing between black and white playing there first.
Another refinement humans use is the heuristic of doubling the value of
a "sente" move - one that creates a big follow-up should the opponent
ignore it and take sente. (presumably the logic is that because it's
sente you get the next move too, which is assumed to be worth the same
as this one).

Given this scheme, a first approximation is to consider sente worth the
difference between the biggest move and the next-biggest move. 

This is rough, but personally I'm more disturbed that my program can't
reliably figure out whether a 50 point group is alive, dead, or
undecided. (but it's getting there...)

-David