Author: Albert Silver
Date: 05:12:17 03/05/02
Go up one level in this thread
On March 05, 2002 at 06:36:58, Ed Schröder wrote:
>On March 05, 2002 at 05:15:38, Uri Blass wrote:
>
>>Yace also likes f5 and has Rh3 in the main line so it seems that finding a
>>better move than Rh3 is not easy.
>>
>>The question is if Rh3 is winning.
>
>I don't know, a further investigation is needed IMO. Rebel gives a +2.30 score
>for Rh3 after 15 plies but probably most of that is coming from eval.
>
>00:00:01.5 1,34 7 416116 Rh3 Kf7 exf5 Bxb3 Qxg6+ Ke7 Rh7+ Rf7
>00:00:02.5 1,34 8 948561 Rh3 Kf7 exf5 Bxb3 Qxg6+ Ke7 Rh7+ Rf7
>00:00:04.9 1,34 9 2379413 Rh3 Kf7 exf5 Bxb3 Qxg6+ Ke7 Rh7+ Rf7
>00:00:08.7 2,22 10 5564762 Rh3 Kf7 exf5 Bxb3 Qxg6+ Ke7 Rh7+ Rf7
>00:00:16.6 2,10 11 12107255 Rh3 Kf7 exf5 Bxb3 Qxg6+ Ke7 Qg5+ Rf6
>00:00:42.6 1,78 12 31920754 Rh3 Kf7 Qh7+ Kf6 Qh4+ Kg7 Bxe6 Qxe6
>00:02:02.0 1,62 13 95158047 Rh3 Kf7 Qh7+ Kf6 Qh4+ Kf7 exf5 Bxb3
>00:06:49.0 2,30 14 322198950 Rh3 Kf7 Qh7+ Kf6 Qh4+ Kg7 Bxe6
>00:14:38.6 2,30 15 688286326 Rh3 Kf7 Qh7+ Kf6 Qh4+ Kg7 Qh7+ Kf6
>
>
>
>>If Rh3 is not winning then it means that Rebel found the right move for the
>>wrong reasons
>
>That's a popular statement in this forum, I once had similar thoughts but
>changed my mind. It does not matter if Nxg6! is played by eval or search, the
>only thing that matters is playing the good move.
Yes and no. Suppose it finds Nxg6 but yields a draw score with a perpetual check
in its main line. Nxg6 is a winning move, so if Rebel were to play it thinking
it drew, how do you know it won't content itself with the draw? Would you
consider it found Nxg6, the _winning_ move, just because it played it? That for
me is the crucial question. I often see programs find a very delicate sacrifice
but with a draw score, and even by feeding them the responses, they do not win
the game. So what then?
Uri's comment here is relevant also because it isn't shown why Rebel immediately
sacs the bishop back with Bc1. No doubt this is the best reply for Black, but
did Rebel do this because it saw a genuine follow-up for White if f5 was played,
or did it see a ghost?
As to the comment on Rh3, it wasn't so much a complaint (I saw the smiley BTW)
as comment on my challenge: find the strongest continuation. In this case, let's
broaden this to find the best continuation after 25.Nxg6 hxg6 26.Qh6 Be6 27.Rd3
f5.
The strongest continuation BTW isn't 28.Rh3, it is 28.Rg3! Rf6 29.Rh3 Kf7
30.Qh7+ Kf8 31.exf5!
I fed this to Fritz 7.0.0.6 and let it run all night on it. It found Nxg6 after
17 plies, but changed it's mind again, and on ply 19 it preferred Nf3 again.
Could you let Rebel run for an hour on the original to see the lines it
produces?
Albert
>>and the question in this case is if Rebel can practically find the
>>winning move in the following position(I did not investigate to find the right
>>move):
>>
>>[D]4qrk1/8/pBn1b1pQ/1p2pp2/4P3/bBPR4/P4PPP/6K1 w - f6 0 4
>>
>>
>>Here is yace main line before f7-f5
>>
>>Analysis by Yace 0.99.56:
>>
>>
>>3...f5 4.Rh3 Kf7 5.exf5 Bxb3 6.fxg6+ Ke7 7.axb3 Rf6 8.Qh7+ Ke6 9.g7 Ne7 10.Rd3
>>Qg6 11.Qh3+ Nf5 12.Bd8
>> ² (0.26) Depth: 12 00:10:16 199936kN
>
>
>[d]4qrk1/8/pBn1b1pQ/1p2pp2/4P3/bBP4R/P4PPP/6K1 b - - 0 1
>
>Following Rebel's analysis
>
>1. Rh3 Kf7 2. Qh7+ Kf6 3. Qh4+ Kg7 4. Bxe6 Qxe6 5. exf5 Qxf5 6. Qh6+ Kf7 7. Rf3
>Qxf3 8. gxf3 1-0
>
>or...
>
>1. Rh3 Kf7 2. Qh7+ Kf6 3. Qh4+ Kg7 4. Bxe6 Qxe6 5. exf5 Qxa2 6. Qh7+ Kf6 7.
>Qxg6+ Ke7 8. Rh7+ Rf7 9. Rxf7+ Qxf7 10. Qxc6 Qxf5
>
>White is a healthy pawn up while the black king is draughty, Rebel's score still
>over 2 pawns, +2.39 to be exactly.
>
>Ed
>
>
>
>
>
>>(Blass, Tel-aviv 05.03.2002)
>>
>>
>>Uri
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