Author: Christophe Theron
Date: 13:04:04 10/11/03
Go up one level in this thread
On October 11, 2003 at 14:12:41, Uri Blass wrote:
>On October 11, 2003 at 14:05:35, Steve Maughan wrote:
>
>>Christophe,
>>
>>>1) I have written an extra engine core ("FUGU") which is extremely "tight". It
>>>updates an internal representation of the board that is simpler than the one
>>>of the classical Tiger engine, and it does not apply all the rules of chess
>>>(some rules like en-passant, castling, underpromoting and 50-moves rule are
>>>complex to handle and slow the engine down significantly). Doing without some
>>>rules in the deepest part of the tree goes mostly unnoticed and help to speed
>>>the engine up tremendously.
>>
>>Now that is an interesting idea. I have heard of top programs that ignore some
>>rules for the whole of the search tree (e.g. Junior 5 ignored underpromotion)
>>but I haven't heard of anyone ignoring some rules when near the tips of the tree
>>(which is most of the search).
>>
>>Regards,
>>
>>Steve
>
>I guess that ignoring the rules is dependent on alpha and beta(otherwise it is
>dangerous because the program may see mate based on the assumption that the
>opponent cannot play an enpassant capture and only later consider the capture
>and find that the mate was an illusion).
>
>I hope that at least when new tiger announce mate it does not prune enpassent
>captures or underpromotions of the opponent.
>
>Uri
This technique can be indeed extremely dangerous. The FUGU engine, by a strict
definition, does not play chess!!!
But it's not new. As you say, the previous versions of Junior were not playing
chess but a slight variant of chess. However it was playing chess brilliantly.
I must pay attention to some cases like the one you mention.
In this case FUGU would not say it's a checkmate. It would just return a low
score (alpha). So far I have never seen any problem because of it.
Christophe
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