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Subject: Re: R+Ps vs R+Ps

Author: Peter McKenzie

Date: 20:54:52 09/07/01

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On September 07, 2001 at 22:15:32, Jim Monaghan wrote:

>Hi Peter,
>
>Here is a difficult R+P endgame for programs illustrating the power of connected
>passers vs scattered ones.
>
>[D] 8/5k2/R5pp/3pP2P/p2r1PK1/8/8/8 b - - 0
>
>Karpov - Deep Thought, 1990.
>
>Deep Thought played the greedy 1...gxh5+?? and Karpov quickly showed the power
>of connected passed pawns in this type of ending:
>
>1... gxh5+ 2. Kf5! (Not 2. Kxh5? Rxf4) Kg7 3. Ra7+ Kf8 4. e6 Re4 5. Rd7 Rc4 6.
>Rxd5 h4 7. Rd3
>Ke7 8. Rd7+ Kf8 9. Rh7 h5 10. Ke5 h3 11. f5 Kg8 12. Rxh5 a3 13. Rxh3 a2 14. Ra3
>Rc5+ 15. Kf6 (1-0)
>
>Absolutely essential was 1...g5! to break up White's pawns at all costs, viz.
>
>1... g5 2. Rxh6 Rxf4+ (Not 2...gxf4? 3. Kf5!) 3. Kxg5 Rf1 should hold.
>
>(Source: Practical Endgame Play, N. McDonald)
>
>I tried this on a few engines and they seem very confused. I suppose it would
>take a very long think on an engine's part to work it all out, if at all.
>Rather than solving it thematically (intuiatively?) as a human would. Knowledge
>vs Brute Force. It's possible that positions like this would show more of an
>engine's shortcomings as opposed to tactical tricks in most endgame studies.

Yes, its the type of position that is a good test of positional knowledge.  But
I'm not 100% convinced that gxh5 is so bad.

After 1...gh 2.Kf4 how about 2...h4!?
I analysed this with LambChop for a while, and it is by no means clear.  Black
even wins if white is not careful.

While I wouldn't be surprised if white has a win, I would be equally unsurprised
if black is holding.  GMs (and McDonald isn't the strongest GM around) can
easily make mistakes in these complex endgames.

Peter

>
>Cheers,
>Jim



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