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Subject: Re: Recapture Extension

Author: Bas Hamstra

Date: 06:41:07 01/11/02

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On January 11, 2002 at 06:33:00, Ulrich Tuerke wrote:

>On January 11, 2002 at 04:59:14, Tony Werten wrote:
>
>>On January 11, 2002 at 04:43:58, Ulrich Tuerke wrote:
>>
>>>Hi Bas,
>>>
>>>>...
>>>>- only recaps to same square
>>>>- the cap-recap sequence must have same material gain
>>>
>>>Why this ?
>>>I'd thought, that the idea is to follow forced lines deeper (e.g. capture and
>>>subsequent re-capture of a pawn). Otherwise the program could use these
>>>recapture sequences to shift events beyond the horizon.
>>>
>>>Thus, I would rather think of sequences, which do not disturb the material
>>>balance.
>>
>>That's an addition that limits the extensions even more: Material ballance must
>>be higher than alfa-2 pawns and smaller than beta+2 pawns.
>
>alfa-2 doesn't imply a material gain at all, but could be very well a loss.
>So, I guess that Bas does it in another way than you.
>
>OTOH, your condition seems quite intutive to me, but it was stated:
>" the cap-recap sequence must have same material gain "
>
>>
>>>
>>>When you restrict these to material wins, it seems to me that you are thinking
>>>of avoiding traps ?
>>
>>He doesn't. He means that the captures must have the same value. ie oppo takes
>>knight, I take bishop, or oppo takes rook I take rook.
>
>But Bas told differently, didn't he ? That's not just a material gain.
>
>Ciao,
>Uli
>>

No, I meant exactly what Tony describes. Precisely what Crafty does, in fact.
But I have experimented with many different versions. You can skip the condition
of equality, and solve many combinations faster. But in games I did not like it.
I even tried capture extensions (0.25 ply fractional). I remember it scored a
lot of draws then, for some reason. Tactically it could not be fooled, but it
lacked the depth to accomplish something useful itsself. Even 0.25 for a capture
costs enourmously in terms of positional depth.


Best regards,
Bas.
















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