Author: Vasik Rajlich
Date: 03:42:36 05/31/05
Go up one level in this thread
On May 30, 2005 at 18:40:21, Gian-Carlo Pascutto wrote: >On May 30, 2005 at 17:44:03, Ricardo Gibert wrote: > >>>No. In fact it increases it significantly. In Cray Blitz, it reduced our >>>average search depth about 2 plies. Which is a significant _increase_ in >>>effective branching factor. >> >>Most extentions result in a reporting of lower depth and an increase in nodes, >>but this usually still means a reduction in ebf, because the depth reported does >>not take into account the additional depth from the extentions. In short, the >>depth reported underrepresents effective depth. As for SE I don't much about it, >>but it must be a pretty crappy extention if it really increases EBF. > >By this redefinition of EBF, I don't immediately see how any technique *can* >have any effect on the EBF. > >An extension would decrease the nominal depth, but this "doesn't count", because >the amount of nodes searched stay the same and the effective depth is deeper. > >A pruning would increase the nominal depth, but that doesn't count either, >because the effective search depth is deeper. > >Even nullmove probably doesn't improve the EBF here - the reduced depth searches >mean that the effective depth is also significantly lower. > >What you're saying is that the NPS is constant, I think. Yes...but...so what? > >I don't think that your line of reasoning makes any sense. And I also really >fail to see how the usefulness of an extension can be defined by it's effect on >the branching factor. > >-- >GCP You could try to redefine EBF so that a good extension decreases it while a bad extension increases it. It would be something along the lines of "depth of important variations". Maybe it's impossible to do it formally. For example "depth of the PV" is going to be related, but not quite correct. Anyway, if you could do this, it would measure true search efficiency. EBF as it is currently defined means nothing - it tells you basically if you prefer to formulate selectivity via extensions, or via pruning/reductions. Vas
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.