Author: Robert Hyatt
Date: 20:07:56 09/20/99
Go up one level in this thread
On September 20, 1999 at 22:45:44, leonid wrote: >On September 20, 1999 at 22:25:41, KarinsDad wrote: > >>On September 20, 1999 at 18:02:23, leonid wrote: >> >>>On September 20, 1999 at 15:22:16, KarinsDad wrote: >>> >>>>On September 20, 1999 at 14:47:49, leonid wrote: >>>> >>>>[snip] >>>>> >>>>>My engin: 6 plys 0.22 sec. 8 plys 18 sec. 10 plys 14min. and 54 sec. >>>>> >>>>>Rebel 10: 2.6 sec 40 sec 12min. and 8 sec. >>>>> >>>>>If my "branching factor" between 6 plys and 8 is 82, for Rebel it is only >>>>>15.3. This is how Rebel take over on the 10 ply. Number of positions per >>>>>second are almost indentical but my are higher. Average number of nodes >>>>>per ply is 36. >>>>> >>>> >>>>Well, it appears that the branching factor for your program (2 ply) from ply 8 >>>>to 10 is 49.7 whereas Rebel's is 18.2. So, your branching factor from ply 8 to >>>>ply 10 is dropping relative to your branching factor from ply 6 to ply 8. Rebel >>>>on the other hand has a slightly increasing branching factor from ply 8 to ply >>>>10 relative to it's ply 6 to ply 8. >>>> >>>>So, whatever the problem is, it does appear to be based on the position (i.e. >>>>some set of positions give you a much greater branching factor relative to Rebel >>>>than another set 2 ply higher). Since pure Alpha Beta should have a ballpark of >>>>a 2 ply branching factor of 36 for the position you are examining, I would guess >>>>that you have a mistake somewhere in that portion of the algorithm. Maybe >>>>assigning Beta to a bound when you should assign Alpha or something along those >>>>lines. >>>> >>>>KarinsDad :) >>> >>>Will be nice if you could explain me the last sentence of your response. >>>And also what is the "Ballpark"? >>>Thanks, >>>Leonid. >> >>Basically, your branching factors (82 and 50) are much higher than normal Alpha >>Beta (which for 2 ply should result in a value of about 36). Therefore, it seems >>that either you are not using Alpha Beta, or you have a mistake in your Alpha >>Beta such as assigning a Beta value to a bound on a cutoff instead of assigning >>an Alpha value to it or some such. >> >>"Ballpark" is a reference from American baseball where if a ball is hit inside >>the ballpark, it is still in play. If it is hit outside the ballpark, it is a >>home run (and out of play). Somehow, this became an expression that means that >>something is within a reasonable value (i.e. in the ballpark). It is often used >>with guesses as per "My guess is x which I know is off, but it is in the >>ballpark.". So in this case, a value of 36 is a reasonable value (in the >>ballpark) for a ply 2 branching factor for the position that you examined. >> >>KarinsDad :) > >Thanks for your response! >Your saying that around 6 nodes must be seen inside of 36 in the ply >correspond 100% of what I found in the best games. My logic all the time did >worst that this, around 8 from 36. Will try to figure out where those >bounds are wrong. > >With my respect, >Leonid. It also might not be a bug, but might be caused by poor move ordering, as that can blow up the search similar to what you are seeing..
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