Computer Chess Club Archives


Search

Terms

Messages

Subject: Some tree numbers

Author: Ralf Elvsén

Date: 07:20:52 06/29/01


Some time ago I discussed with Terrapong the ratio of
makemove/movegenerations. I don't think this is what he
was asking for, but I got interested anyway:

Given alphabeta with perfect move ordering and a branching
factor = w (effective branching factor = sqrt(w) ), what is the ratio
of makemove/movegenerations ?

I have asymptotic expressions for "reasonably big" depths:

For even search depths: the ratio is (3w + 1)/(w + 3)
For odd search depths: the ratio is w*(w + 3)/(3w + 1)

There is a pretty extreme odd-even effect. For e.g. w = 36
we have 2.8 (even) and 12.9 (odd).

Nothing of this applies when nullmove and hashtables are considered
of course...

I have checked this reasonably well, but I am under a curse which
doesn't allow me to get calculations right the first time...

If you want to see some other numbers, I'll see what I can do :)

Ralf



This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.