Author: Vasik Rajlich
Date: 08:45:45 09/04/05
Go up one level in this thread
On September 04, 2005 at 05:46:03, Mridul Muralidharan wrote: >On September 04, 2005 at 04:42:11, Vasik Rajlich wrote: > >>On September 03, 2005 at 15:41:48, Mridul Muralidharan wrote: >> >>>[D]r2q3r/1b1k1pbp/p4np1/2BP1pN1/p1B5/P1Q5/1PP3PP/R3K2R w KQ - 0 19 >>> >>>My engine royally blows up when it comes to this position (arrived at a game >>>against some engine a long while ago). >>>I suspected excessive extensions , qsearch problems , eval inconsistencies , >>>bugs , etc. >>>Could not find any bugs and there were no obvious others problems ... the >>>position just kills the node count. >>>Analysed it with other engines and most if not all had similar problems. >>> >>>I have not done an actual position analysis of the position with a strong player >>>(that is tactics , positional aspects , etc - just analysed the stats that my >>>engine dumps for this pos). >>> >>>Any comments ? >>> >>>Thanks, >>>Mridul >> >>This reminds me of a funny position I saw the other day: >> >>[D] r1r3k1/1bq1bppp/p1npp1P1/2nB1N1Q/1p2P3/2N1B3/PPP2P1P/2KR2R1 b - - >> >>I was doing a q-search test which assumed that no q-search would go over 10k >>nodes. This one crashed it :-) >> > >Tough position this one too , thanks ! >I want to address positions like this upfront so that there is a lower bound to >the worst case behaviour >My idea is to play around and research about move ordering , extensions and >qsearch/eval .. overall program strength/weakness is just a sideeffect as of now >:) Actually, this position is more for amusement. If every position was like this, q-search would need to work differently - but it's not .. > >I did not understand "I was doing a q-search test which assumed that no q-search >would go over 10k nodes" - what exactly did you mean ? > Just a funny debugging story. (Unfortunately I have a bit more of those than I'd like.) I set up a test which just calls the q-search. There was a hard-coded constant so that it could only handle a q-search of <10,000 positions. Seems safe enough, right? :-) Vas >- Mridul > >>Here is the ridiculous source game: >> >>[Event "Engine Games 003 Min + X Sec"] >>[Site "Internet"] >>[Date "2005.01.17"] >>[Round "?"] >>[White "Deep Fritz 8"] >>[Black "Fritz 8"] >>[Result "1-0"] >>[ECO "B89"] >>[WhiteElo "2578"] >>[BlackElo "2494"] >>[PlyCount "89"] >>[EventDate "2005.??.??"] >>1. e4 c5 2. Nf3 e6 3. Nc3 d6 4. d4 cxd4 5. Nxd4 Nc6 6. Be3 Nf6 7. Bc4 a6 8. Qe2 >>Be7 9. Bb3 Qc7 10. O-O-O O-O 11. Rhg1 Nd7 12. g4 Nc5 13. Nf5 b5 14. Bd5 Bb7 15. >>g5 Rfc8 16. Qh5 b4 17. g6 hxg6 18. Rxg6 fxg6 19. Qxg6 Bf6 20. Bxc5 Qd7 21. Rg1 >>Rf8 22. Bxd6 Rae8 23. Na4 exd5 24. Nc5 Qxf5 25. exf5 Ne7 26. Qh5 Bc6 27. Ne6 >>Rf7 28. Bxe7 Rfxe7 29. Qh6 Rf8 30. h4 Bb7 31. Qg6 Rff7 32. Rg5 Rxe6 33. fxe6 >>Bxg5+ 34. Qxg5 Rf6 35. Qe5 Bc6 36. Qb8+ Kh7 37. e7 Rxf2 38. e8=Q Bxe8 39. Qxe8 >>Rf1+ 40. Kd2 Rf5 41. Qe6 Rh5 42. Qg4 Re5 43. Qxb4 Re4 44. Qb6 Ra4 45. h5 1-0 >> >>Vas
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