Author: Christophe Theron
Date: 14:05:06 09/27/00
Go up one level in this thread
On September 27, 2000 at 06:34:50, Aaron Tay wrote:
>On September 27, 2000 at 04:07:45, Uri Blass wrote:
>
>>On September 27, 2000 at 03:20:21, Aaron Tay wrote:
>>
>>>On September 26, 2000 at 15:01:19, Christophe Theron wrote:
>>>
>>>>On September 26, 2000 at 09:31:30, Bas Hamstra wrote:
>>>>
>>>>>It seems the current LG versions are nps wise down to slightly faster than
>>>>>Crafty :) I play it all the time at FICS. It seems is evolving to a slower and
>>>>>more knowledgable program. As is mine, BTW :)
>>>>>
>>>>>On September 25, 2000 at 01:38:15, Jouni Uski wrote:
>>>>>
>>>>>>In my moderate AMD K6-2 450Mhz and 50 MB hash it exceeds easily 1000knps in
>>>>>>tactical positions and sometimes goes over 1300knps. Of course I know this means
>>>>>>almost nothing to playing strength, but still it's unbelievable. I wonder can
>>>>>>it be true nps value or has Michael B. his own node definition...
>>>>>>
>>>>>>Jouni
>>>>
>>>>
>>>>
>>>>Don't mix up "slower NPS" and "more knowledge". They have nothing to do with
>>>>each other.
>>>>
>>>>In my example, I have said how I could make Tiger much faster just by turning
>>>>off some obvious selection schemes. If I turn these selection algorithms back
>>>>on, then the program is suddenly much slower. It is also much stronger.
>>>>
>>>>But the amount of "knowledge", as most people understand by "knowledge" has NOT
>>>>changed at all. I mean that the evaluation of chess positions is still exactly
>>>>the same. If the program does not understand a knight outpost in the fastest
>>>>version, then it still does not understand it with the slower version.
>>>>
>>>>When a new version of a known program is released, some people will look at the
>>>>NPS and say "Oh, the NPS of the new version is lower, so I guess more knowledge
>>>>has been added to the program". Bullshit.
>>>>
>>>>
>>>>
>>>> Christophe
>>>
>>>
>>>Sorry but talking as a person who knows nothing sbout chess programming, isn't
>>>it true that the more complicated evalution functions you add, the slower the
>>>search becomes to reach the same depth?
>>
>>The main point is that there are other reasons to be slower(more complicated
>>search rules or different definition of nodes) and you cannot know the reason
>>for being slower so you cannot say that a program that needs more time to >search the same number of nodes has more complicated evaluation function.
>
>>The discussion was about nodes per second and not about being faster or slower
>>in reaching the same depth.
>>
>>You can be slower in reaching the same depth by not prunning lines by null >moves or other prunning ideas so the depth tells nothing about the complexity >of evaluation.
>
>Oops poor choice of words..But generally more complicated evalutation/knowledge
>= lower NPS?
>
>
>Of course as the thread above says, you can have lower NPS for other reasons..
>
>
>Christophe mentions "switching off obvious selection schemes" to speed up Tiger,
>what exactly does that mean?
>
>For example,
>Does he mean switching from a more complicated adaptive null move pruning method
>where R=2 or 3 depending on sitution to a simpler say null move R=2 througout
>will increase NPS also?
>
>
>But does it really cost so much more?
No, I wasn't talking of playing with null move. Null move is only ONE
selectivity algorithm, but there are DOZENS of other ways to be selective and
gain strength from selectivity.
>So with all things equal , as your search becomes more complicated, NPS
>drops..Eg from a simple search add Killer moves, Quience search then null move
>and NPS drops furthur??
Yes. Adding a QSearch to an existing program drops the NPS tremendoulsy for
example. Because generating only capture moves takes more time in average per
generated move than generating all the possible moves in a position.
You add QSearch => your NPS drops. But the program plays much better.
This is just an example, but there are a lot of others.
That's why I say there is no relationship between NPS and playing strength, and
no relation between NPS and amount of knowledge.
As far as I know, null move has almost no impact on the NPS.
Christophe
>>Another point is that it is possible that a more complicated evaluation will
>>help you to get bigger depth because the evaluation may help you to get a >better order of moves.
>
>Agreed .
>
>NPS may be irrelevant. Kasparov has a low NPS compared to computers but because
>of better "move order" so beta cutoffs come quickly and singular extensions , he
>can usually search a deeper depth..
>
>>Uri
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