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Subject: Re: Example for the potential of the new Botvinik-Makaroff-Threat-Extensions

Author: Uri Blass

Date: 07:47:35 10/02/03

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On October 02, 2003 at 10:30:35, Grzegorz Sidorowicz wrote:

>On October 02, 2003 at 10:20:26, Tim Foden wrote:
>
>>On October 02, 2003 at 09:49:18, Grzegorz Sidorowicz wrote:
>>
>>>
>>>>Which GLC reckons is a mate in 6 for Black...
>>>>
>>>> 10   8.642 +Mate06  19660k  Kb5 8. b4 d1=Q 9. Ke5 Qd2 10. Bc5 Kc6 11. Ke6 Qe2+
>>>>                               12. Be3 Qxe3#
>>>>
>>>>So I'm confused... are you saying that Nc6 is the solution, or the wrong move?
>>>>
>>>>Cheers, Tim.  :)
>>>
>>>What your program doing when in qsearch is check?
>>>
>>>Grzegorz
>>
>>Nothing.  It doesn't detect checks in qsearch, it doesn't generate checks in
>>q-search (unless a capture causes a check).
>>
>>It does, however, always extend on a check on the last ply of search, so, in
>>fact, the first level of q-search can never include a check.
>>
>>Cheers Tim.
>
>
>I think in this position it is very impoprtant.
>My program without checks in qsearch is slow as turtle in honey.
>In other words without it this positions are impossible to solve by Armageddon.
>Checks in qsearch are vey important. I don't know why people not use it in
>qsearch. Program with it can be slow of course but I not use it always.
>I use it always in lines where are many checks, because there are important.
>This formula is only a little slower than qsearch without checks.

This is the main line that your program needs to see:

1.Nc6+ Kb7 2.Na5+ Kb6 3.Bf2+ Kxa5
4.e8Q Nc7+ 5.Kd6 Nxe8
6.Kc5 d2 7.Bd4 d1N
8.Be5 f2
9.Bf4 f1N
10.Bg5 Nf6
11.Bxf6 Nf7
12.Bh4 Nf2
13.Bxf2 Nd2
14.Be1 Be2
15.Bxd2#

Can you explain how checks in the qsearch help you to extend 14.Be1 Be2?

Uri



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