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Subject: Re: evaluation tuning tricks

Author: milix

Date: 11:17:45 03/17/04

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On March 17, 2004 at 11:02:13, Renze Steenhuisen wrote:

>On March 17, 2004 at 05:26:50, milix wrote:
>
>>On March 17, 2004 at 04:58:06, Peter Alloysius wrote:
>>
>>>what are tricks for evaluation tuning so that it could
>>>search less nodes?
>>>
>>>i noted that my engine use exactly same move ordering scheme as
>>>crafty but it still search much more nodes.
>>>my engine also use adaptive null move, and futility pruning.
>>>
>>>so i think the problem is on evaluation tuning.
>>>i heard that tuning evaluation function can reduces node searched,
>>>so what's the trick?
>>
>>I think that there is no special trick. A bad evaluation will missguide the
>>search. When I turn off the positional evaluation (and have only material+piece
>>square scores) my engine is doing too many researches and the move ordering is
>>also very bad. Same effect if I alter a positinal characteristic too much, like
>>giving a very big bonus in advanced pawns or penalize bad king safety too much.
>
>If you turn positional evaluation off, what are typical numbers for
>move-ordering? Because this is exactly what I do for now, but the History
>Heuristic nor Killer Heuristic don't give very nice move-ordering %'s!
>
>Thanks!
>
>Renze

I think both heuristics are suffer for bad evaluation especially when going
deeper in the search tree. To test the bad behaviour of a weak evaluation you
can set the rook value to 2 pawns and see what happens in your search especially
in middle-game to end-game positions.



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