Author: Gerd Isenberg
Date: 10:37:12 11/08/02
Go up one level in this thread
On November 08, 2002 at 10:56:03, Uri Blass wrote:
>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.
May be, that was the intention of the initial question.
But if alpha in some subtrees already has a winning score, doesn't mean the game
is over. Possibly Grzegorz (corrected) statement will safe some nodes in not
important subtrees, specially for static 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.
>
If you aleady detects singularity, why not using this information for some more
fractional plies in possible critical variations?
>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.
>
Don't think so, at least in my program. My eval detects most mates in one or
even in N moves.
Gerd
>Uri
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