Author: KarinsDad
Date: 19:25:41 09/20/99
Go up one level in this thread
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 :)
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