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Subject: Re: If you are in to deep mates.

Author: Dieter Buerssner

Date: 06:56:14 01/05/02

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On January 04, 2002 at 22:42:26, Dan Andersson wrote:

>[D]1R6/6pK/5p2/4p3/1B1p3n/8/p1p1pp2/1k3b2 w - - 0 1
>Krabbé (1985)
>
>I have posted it before.

I tried this with Yace, running in the background with 20M hash:


  55962675  5:52.0   0.00 15.  1. Ba3+ Ka1 2. Bb2+ Kb1 3. Ba3+ {-480}
  92238734  9:44.2  Mat38 16++ 1. Ba3+ Ka1 2. Bb2+ Kb1 3. Bxd4+ Kc1 4. Be3+
                               Kd1 5. Rd8+ Ke1 6. Bd2+ Kd1 7. Bb4+ Kc1 8. Ba3+
                               Kb1 9. Rb8+ Ka1 10. Bb2+ Kb1 11. Bxe5+ Kc1 12.
                               Bf4+ Kd1 13. Rd8+ Ke1 14. Bd2+ Kd1 15. Bb4+ Kc1
                               16. Ba3+ Kb1 17. Rb8+ Ka1 18. Bb2+ Kb1 19.
                               Bxf6+ Kc1 20. Bg5+ Kd1H 21. Rd8+H Ke1H 22.
                               Bd2+H Kd1H 23. Bb4+H Kc1H 24. Ba3+H Kb1H 25.
                               Rb8+H Ka1H 26. Bb2+H Kb1H 27. Bxg7+H Kc1H 28.
                               Bh6+H Kd1H 29. Rd8+H Ke1H 30. Bd2+H Kd1H 31.
                               Bb4+H Kc1H 32. Ba3+H Kb1H 33. Rb8+H Ka1H 34.
                               Be7H c1=QH 35. Bf6+H Qb2H 36. Rxb2H e1=QH {HT}
                               {-1001}

But it lost the mate again later. This was also not unsurprising, because Yace
has by default a maximum ply of 62, which is not enough here. So, the mate can
only be found with support (and luck) from the hash tables.

Out of curiosity, I made 2 very small changes: Doubling the maximum ply and also
limiting check extension less:

  10040485  1:25.2  Mat38 11++ 1. Ba3+ Ka1 2. Bb2+ Kb1 3. Bxd4+ Kc1 4. Be3+
                               Kd1 5. Rd8+ Ke1 6. Bd2+ Kd1 7. Bb4+ Kc1 8. Ba3+
                               Kb1 9. Rb8+ Ka1 10. Bb2+ Kb1 11. Bxe5+ Kc1 12.
                               Bf4+ Kd1 13. Rd8+ Ke1 14. Bd2+ Kd1 15. Bb4+ Kc1
                               16. Ba3+ Kb1 17. Rb8+ Ka1 18. Bb2+ Kb1 19.
                               Bxf6+ Kc1 20. Bg5+ Kd1 21. Rd8+ Ke1 22. Bd2+
                               Kd1 23. Bb4+ Kc1 24. Ba3+ Kb1 25. Rb8+ Ka1 26.
                               Bb2+ Kb1 27. Bxg7+ Kc1 28. Bh6+ Kd1 29. Rd8+
                               Ke1 30. Bd2+ Kd1 31. Bb4+ Kc1 32. Ba3+ Kb1 33.
                               Rb8+ Ka1 34. Be7H c1=QH 35. Bf6+H Qb2H 36.
                               Rxb2H e1=QH 37. Rb6+H Qe5H 38. Bxe5#H {HT} {0}
  19838909  2:36.7  Mat38 11t  1. Ba3+ Ka1 2. Bb2+ Kb1 3. Bxd4+ Kc1 4. Be3+
                               Kd1 5. Rd8+ Ke1 6. Bd2+ Kd1 7. Bb4+ Kc1 8. Ba3+
                               Kb1 9. Rb8+ Ka1 10. Bb2+ Kb1 11. Bxe5+ Kc1 12.
                               Bf4+ Kd1 13. Rd8+ Ke1 14. Bd2+ Kd1 15. Bb4+ Kc1
                               16. Ba3+ Kb1 17. Rb8+ Ka1 18. Bb2+ Kb1 19.
                               Bxf6+ Kc1 20. Bg5+ Kd1 21. Rd8+ Ke1 22. Bd2+
                               Kd1 23. Bb4+ Kc1 24. Ba3+ Kb1 25. Rb8+ Ka1 26.
                               Bb2+ Kb1 27. Bxg7+ Kc1 28. Bh6+ Kd1 29. Rd8+
                               Ke1 30. Bd2+ Kd1 31. Bb4+ Kc1 32. Ba3+ Kb1 33.
                               Rb8+ Ka1 34. Be7 c1=Q 35. Bf6+ Qb2 36. Rxb2
                               e1=Q 37. Rb6+ Qe5 38. Bxe5# {0}
  20038704  2:39.1  Mat38 11.  1. Ba3+ Ka1 2. Bb2+ Kb1 3. Bxd4+ Kc1 4. Be3+
                               Kd1 5. Rd8+ Ke1 6. Bd2+ Kd1 7. Bb4+ Kc1 8. Ba3+
                               Kb1 9. Rb8+ Ka1 10. Bb2+ Kb1 11. Bxe5+ Kc1 12.
                               Bf4+ Kd1 13. Rd8+ Ke1 14. Bd2+ Kd1 15. Bb4+ Kc1
                               16. Ba3+ Kb1 17. Rb8+ Ka1 18. Bb2+ Kb1 19.
                               Bxf6+ Kc1 20. Bg5+ Kd1 21. Rd8+ Ke1 22. Bd2+
                               Kd1 23. Bb4+ Kc1 24. Ba3+ Kb1 25. Rb8+ Ka1 26.
                               Bb2+ Kb1 27. Bxg7+ Kc1 28. Bh6+ Kd1 29. Rd8+
                               Ke1 30. Bd2+ Kd1 31. Bb4+ Kc1 32. Ba3+ Kb1 33.
                               Rb8+ Ka1 34. Be7 c1=Q 35. Bf6+ Qb2 36. Rxb2
                               e1=Q 37. Rb6+ Qe5 38. Bxe5# {0}

And keeps this line.

I think, a search specially tuned for this could be extremely fast. For
practical games, it is probably not helpful and even hurting.

Regards,
Dieter




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