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Subject: Re: Does crafty stop calculating SEE after capturing a king?

Author: Robert Hyatt

Date: 07:16:13 01/13/04

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On January 13, 2004 at 09:31:01, scott farrell wrote:

>On January 13, 2004 at 09:24:56, Robert Hyatt wrote:
>
>>On January 13, 2004 at 03:48:32, Andreas Guettinger wrote:
>>
>>>On January 12, 2004 at 17:47:07, Robert Hyatt wrote:
>>>
>>>>On January 12, 2004 at 17:34:52, Uri Blass wrote:
>>>>
>>>>>I do not see when it happens in crafty and note that it is not only a question
>>>>>of speed when it is not clear what is faster and if I understand correctly
>>>>>crafty may be wrong when a sequence of captures that is finished in trading
>>>>>kings happens and it may happen in the endgames.
>>>>>
>>>>>[D]8/5r2/5k2/3R1p2/5K2/8/8/8 w - - 0 1
>>>>>
>>>>>Rxf5+ is a good capture but based on SEE that let trading kings it can be
>>>>>pruned.
>>>>>
>>>>>Uri
>>>>
>>>>No.  It is not very frequent and doing the test will burn more time than
>>>>avoiding the test saves, since the occurrence is so tiny.  I simply ignore
>>>>it totally...
>>>
>>>A gave my kings a value of +-Infinity.
>>>Now, in such a case, wouldn't it stand pat anayway instead of capturing the
>>>king? Because loosing a rook seems better than loosing a king.
>>>
>>>regards
>>>Andy
>>
>>
>>I do the same, so actually you might be correct, in that losing one king will
>>stop the captures there in the minimax phase...
>
>I think you'll find URI set this up specifically, notice the rook _behind_ the
>king, ready for an xray attack.
>
>if you take my King, I'll take yours with my rook !!!
>
>Scott

I understood that for this case.  And, as I said, it doesn't work correctly.
However, for the _far_ more common case where a king is one of the attackers/
defenders, and only one king is involved, it works fine, even though it has
the x-ray attacker/defender behind the king.

I don't consider this to be significant enough to think about, myself.  It would
be easy to fix, but it would be a tad slower.  SEE is already wrong too many
times, such as with overloaded and pinned pieces...



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