Author: Uri Blass
Date: 07:56:03 11/08/02
Go up one level in this thread
On November 08, 2002 at 10:13:44, Gerd Isenberg wrote:
>On November 08, 2002 at 09:48:13, Uri Blass wrote:
>
>>On November 08, 2002 at 08:50:46, Gerd Isenberg wrote:
>>
>>>On November 08, 2002 at 07:01:15, Grzegorz Sidorowicz wrote:
>>>
>>>>What do you think about formula?
>>>>
>>>>if (!(alpha>(CHECKMATE-QVALUE)))
>>>>{
>>>> do_not_extent=true;
>>>>}
>>>>
>>>>Currently I'm testing this formula for all extensions
>>>>and for example I have got 5 solutions more in WAC test...
>>>>but now my program can't solve some other positions
>>>>(for example CMB-10 from LCTII test)
>>>>
>>>>Grzegorz
>>>
>>>Hi Grzegorz,
>>>
>>>I suppose you want to disable extensions, if alpha is already a winning score.
>>>Is the not operator correct, or what is your intention?
>>>
>>>Gerd
>>
>>I do not understand this idea.
>>
>>If alpha is already a winning score then it means that beta is also winning
>>score so the game is over.
>
>Yes, so doing further extensions now may be a waste of time.
When the game is already over it is not very important if you do more
extensions.
The question if you do extensions is important when the root position is not
clear and in this case alpha is not going to be a winning score unless you find
a win for your opponent and in that case you can not investigate the exact score
but search the other moves.
Using the evaluation instead of alpha seems more logical but if you have not
incremental evaluation you may need to spend time for it or use lazy evaluation.
>
>>
>>The only case when it may be relevant is if you search not in a normal way(for
>>example search for exact score of the second best move)
>>
>>It is one of the ideas that I consider to try in the future(but of course I need
>>to do it to reduced depth in order not to waste too much time about it).
>>
>>Wasting a small amount time can be useful to get knowledge(for example you can
>>see if there is a forced move and play it faster if you have an exact score of
>>the second best move)
>
>Similar to singular extensions. No experience with this topic.
Yes
There are similiarities but I do not like the idea of extending singular moves
everywhere in the tree and the exact score may be used also for pruning and not
also for exatensions.
An extreme example is that if you find an exact mate score for a position then
you never need to search it in the future.
In the normal way you will find less exact mate scores and the only case that
you can find a mate score is in case that the move you considered as best has a
mate score and this is rare.
Uri
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