Author: Heiner Marxen
Date: 11:04:54 10/28/01
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On October 28, 2001 at 13:33:17, Robin Smith wrote: >On October 28, 2001 at 10:55:27, José Carlos wrote: > >>On October 28, 2001 at 06:53:06, José Carlos wrote: >> >>> I managed to make EGTB's work properly except in positions with pawn/s. I >>>checked the tablebases by making crafty think in some positions; it worked >>>perfectly. For example, in the following position it returns draw: >>> >>>[D]8/7k/5K2/8/2B5/8/7P/8 b - - 0 31 >>> >>> Now, my program says black is checkmated! >>> I tested lots of positions without pawns, and worked fine, so I guess I have a >>>bug somewhere related to pawns, but tracing the program I can't see anything >>>strange. >>> Can anyone please try this position and trace it? >>> My numbers: >>> IDescFindFromCounters (rgiCounters) returns 24 >>> PfnIndCalc(iTb,side) (psqW,psqB,sqEnP,fInvert) returns 1557728 >>> L_TbtProbeTable (iTb,side,ind) returns 32766 (the checkmate!!) >>> >>> Do you guys get the same numbers? Anyone got a clue what I'm doing wrong? >>>Should I post some code so you can check? >>> >>> Thanks in advance, >>> >>> José C. >> >> As I started the amalisys, the given data is for the position after ...Kh6 >> >> José C. > >Hi Jose, > >The position before Kh6 is drawn. The position after Kh6 white wins. > >For example: > >1... Kh6?? 2. Bd3 Kh5 3. h3 Kh4 4. Bf5 Kh5 5. Kg7 Kg5 6. Bg4 Kh4 7. Kh6 Kg3 8. >Kg5 > >Analyzed without TB's, so there may be a faster win, but you get the idea. > >Robin For the position after Kh6: [D]8/8/5K1k/8/2B5/8/7P/8 w - - Crafty (18.10) with 4-piece EGTBs gives (immediately): Black(2): setboard 8/8/5K1k/8/2B5/8/7P/8 w - - 1. Bd3 Kh5 2. Bf5 Kh4 3. h3 Kh5 4. Kg7 Kg5 5. Bg4 Kf4 6. Kg6 Kg3 7. Kg5 Kf2 8. Kf4 Ke1 9. Ke3 Kf1 10. Bf3 Ke1 11. h4 Kf1 12. h5 Kg1 13. Kf4 Kf1 14. h6 Ke1 15. Ke3 Kf1 16. h7 Ke1 17. h8=Q Kf1 18. Qh1# i.e. Crafty thinks it is a mate in 18. Chest confirms. With debug mode enabled it tells some details: % EGTB found tables for max 4 pieces % EGTB uses 1542.1K memory internally > eg_probe FEN: 8/8/5K1k/8/2B5/8/7P/8 w - - = eg_probe cntarr=1,0,1,0,0,0,0,0,0,0, = eg_probe iTb=24 = eg_probe fInvert=0 = eg_probe sqarr: [0][1] = 17 = 17 [0][2] = 200 [0][3] = 164535332 = 32 [0][4] = 20000000 [0][5] = 0 [0][6] = 55 = 55 [1][1] = 0 [1][2] = 27777706674 [1][3] = 1001657427 [1][4] = 20000000 [1][5] = 10000263340 [1][6] = 57 = 57 = eg_probe sqep=177 = eg_probe ind=3398635 = eg_probe v=32749 < eg_probe q=39 EGTB value = 39 = #18 [Don't worry about those large numbers above, they are meaningless] While our programs agree on the EGTB to use (24) they do not agree about the calculated index to use: yours=1557728, mine=3398635. [My sqep above is octal, the other values are decimal.] Hope this helps. Heiner
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