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Subject: Re: Symbolic progress report

Author: Uri Blass

Date: 11:06:59 12/31/03

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On December 31, 2003 at 13:43:42, Steven Edwards wrote:

>On December 31, 2003 at 13:31:56, Ed Trice wrote:
>
>>This was the Qh5+!! sacrifice, correct?
>
>Yes; a mate in ten.  One variation found by Symbolic's low level search goes:
>
>(1. Qh5+ Nxh5 2. fxe6+ Kg6 3. Bc2+ Kg5 4. Rf5+ Kg6 5. Rf6+ Kg5 6. Rg6+ Kh4 7.
>Re4+ Nf4 8. Rxf4+ Kh5 9. Rg3 Bxe6 10. Bg6#)

This can be solved easily by extending every stupid check that is not first
check by almost 2 plies.

If I tell movei to do it and it means adding almost 1/2 ply check extensions to
checks that are not first check then it can solve it at depth 4 after 87918
nodes that means less than one second.

Note that in that case it does not see mate in 10 but longer mate(mate in 14)

Here is the analysis

1 264 0 142 e5f6 g7f6
2 294 0 283 e5f6
2 294 2 4239 e5f6
3 231 2 4753 e5f6 g8f6 f5e6 d7e6
3 231 8 20161 e5f6 g8f6 f5e6 d7e6
4 183 10 24832 e5f6 g8f6 b3e6 d7e6 f5e6 e8e6
4 184 29 74278 e2h5
4 213 29 74436 e2h5
4 9973 35 87918 e2h5 f6h5 f5e6 f7g6 b3c2 g6g5 f1f5 g5g6 f5f6 g6g5 h2h4 g5h4 e1e
4 h5f4 e4f4 h4g5 f6f5 g5g6 f4g4 g6h7 g4g7 h7h8 g7h7 h8h7 f5f7 h7h8 f7h7
4 9973 35 87958 e2h5 f6h5 f5e6 f7g6 b3c2 g6g5 f1f5 g5g6 f5f6 g6g5 h2h4 g5h4 e1e
4 h5f4 e4f4 h4g5 f6f5 g5g6 f4g4 g6h7 g4g7 h7h8 g7h7 h8h7 f5f7 h7h8 f7h7


Uri



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