Author: Uri Blass
Date: 09:16:10 08/29/04
Go up one level in this thread
On August 29, 2004 at 12:09:32, Anthony Cozzie wrote: >On August 29, 2004 at 11:13:49, Vasik Rajlich wrote: > >>On August 29, 2004 at 09:52:25, Uri Blass wrote: >> >>>On August 29, 2004 at 09:37:13, Uri Blass wrote: >>> >>>>On August 29, 2004 at 08:58:46, Vasik Rajlich wrote: >>>> >>>>>White to play and avoid Rg5. According to my calculations, you'd need a 120-ply >>>>>search to understand that Rg5 draws. >>>>> >>>>>Vas >>>>> >>>>>[D] 8/6k1/4p1r1/4Pp1R/5P2/5K2/7P/8 w - - 0 1 >>>> >>>>You do not need to see that Rg5 draws in order to avoid Rg5 >>>>It is enough to find a move that is evaluated as better. >>>> >>>> >>>>Stupid Movei does not know much about endgame and does not use hash for pruning >>>>but it avoid Rg5 from the first second. >>>> >>>>I guess that after I add some knowledge it may have a problem to avoid Rg5 >>>> >>>>depth=18 +1.75 h2h4 g7f7 h5g5 g6h6 h4h5 h6h8 f3g3 h8h6 g3h4 h6h8 g5g2 h8h7 g2g3 >>>>f7e7 g3g6 e7d7 h4g5 >>>>Nodes: 286711354 NPS: 769922 >>>>Time: 00:06:12.39 >>>>depth=18 +1.75 h2h4 g7f7 h5g5 g6h6 h4h5 h6h8 f3g3 h8h6 g3h4 h6h8 g5g2 h8h7 g2g3 >>>>f7e7 g3g6 e7d7 h4g5 >>>>Nodes: 315137376 NPS: 780448 >>>>Time: 00:06:43.79 >>>>depth=19 +1.77 h2h4 g6h6 h5g5 g7f7 h4h5 h6h8 f3g3 h8d8 h5h6 d8h8 g5g7 f7f8 g7g6 >>>>f8f7 g6f6 f7e7 g3f2 h8h7 f2e3 e7d7 f6g6 d7e7 >>>>Nodes: 393358321 NPS: 781884 >>>>Time: 00:08:23.09 >>>> >>>>Uri >>> >>>There was a reduction at depth 20 so I was interested to see if movei may find >>>Rg5 but it was only a temporary reduction >>> >>>depth=21 +1.93 h2h4 g6h6 h5g5 g7f7 h4h5 h6h8 f3g3 h8d8 h5h6 d8h8 g5g7 f7f8 g7g6 >>>f8f7 g6f6 f7e7 g3f3 h8g8 h6h7 g8a8 f6h6 a8h8 h6h2 e7f7 >>>Nodes: 1287416720 NPS: 795708 >>>Time: 00:26:57.95 >>> >>>Uri >> >>True - really the problem should be for the position after Rg5: >> >>Black to play and report a drawing score. >> >>Vas >> >>[D] 8/6k1/4p1r1/4PpR1/5P2/5K2/7P/8 b - - 0 1 > > >Such positions are incredibly hard - if the whole position is moved back one >rank, white wins: > >1. f5xg6 Kg8-g7 2. Kf4-f5 Kg7-h6 3. h3-h4 Kh6-g7 4. h4-h5 Kg7-h6 5. Kf5-f4 >Kh6-g7 6. Kf4-e4 Kg7-h6 7. Ke4-d5 Kh6-g7 8. Kd5-c6 f6-f5 9. Kc6-d5 Kg7-f6 10. >Kd5-d4 f5-f4 11. Kd4-e4 Kf6-g7 12. Ke4xf4 Kg7-h6 13. Kf4-e5 Kh6-g7 14. Ke5-d5 >Kg7-h6 15. Kd5-c6 Kh6-g7 16. Kc6-d7 Kg7-f6 17. h5-h6 Kf6-f5 18. Kd7xe7 > = MAT28 Depth: 26/37 00:00:07.67 8126kN (1059 KN/s, 0 splits, 0 aborts) > >(With the help of a little backwards analysis) > >If you want a _really_ embarrassing position, try: > >[D]8/1kP5/1P6/6p1/6Pp/5K2/8/8 w - - 0 1 > >1. Kf3-f2 Kb7-c8 2. Kf2-g2 Kc8-d7 3. Kg2-f3 Kd7-c8 4. Kf3-f2 Kc8-b7 5. Kf2-f3 >Kb7-c8 > = (5.67) Depth: 23/38 00:01:41.43 36269kN (358 KN/s, 0 splits, 0 aborts) > >Which zappa scores as almost +6, and is of course drawn. > >anthony This is not so embarassing and movei only has scores near +2 for white. If you want really embarassing position then choose some drawn tablebases drawn position of KQ vs KP or KBP vs K or KNN vs KP. Uri
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