# Computer Chess Club Archives

## Messages

### Subject: Re: Is the NPS for minimax devided by NPS in alpha-beta = 5 ?

Author: leonid

Date: 12:36:09 06/16/00

Go up one level in this thread

On June 16, 2000 at 15:27:42, Tom Kerrigan wrote:

>On June 16, 2000 at 14:54:18, leonid wrote:
>
>>On June 16, 2000 at 14:12:47, Tom Kerrigan wrote:
>>
>>>On June 16, 2000 at 14:10:24, leonid wrote:
>>>
>>>>On June 16, 2000 at 13:25:41, Tom Kerrigan wrote:
>>>>
>>>>>On June 16, 2000 at 13:16:57, leonid wrote:
>>>>>
>>>>>>On June 16, 2000 at 12:34:58, Michel Langeveld wrote:
>>>>>>
>>>>>>>No nps of alpha-beta and minimax will be almost the same. But the total number
>>>>>>>of and the total amount of time will be a much lesser.
>>>>>>
>>>>>>Your first statement sound to me as something near to impossible. Just recently
>>>>>>Bas Hamstra said that minimax speed is around 800000 nodes/second. Computer was
>>>>>>indicated as Pentium 466M. Usual number of nodes/second that I see on my AMD
>>>>>>400M (for some best chess games like: Crafty, Xchess, Comet...)is around 150000.
>>>>>>Even from this I can see that: 800000:150000=5.3 times.
>>>>>
>>>>>Then his program is 5.3 times faster. This has virtually nothing to do with
>>>>>alpha beta vs. minimax.
>>
>>So, what your obove sentence say? In simple term? That 800000 NPS is just usual
>>speed (or more exactly, number of positions seen) of its program? Never mind if
>>logic use minimax or alpha-beta? Number of positions seen is always 800k?
>
>Exactly.
>
>Just think about it. What do you do in a node? Positional evaluation, move
>generation, etc. If you switch from alpha-beta to minimax, does that mean you
>magically have to do less work per node? No. So the speed should be exactly the
>same. (Well, maybe not exactly, but at least approximately.)

Very interesting! I just found above your numbers and they are very close.
Exactly like you say. My number is 400% different. Strange!

Leonid.

>It's not a very interesting question, though. Anybody who's smarter than a rock
>will use alpha-beta because it's infinitely more efficient than minimax.
>
>-Tom