Author: Robert Hyatt
Date: 14:04:03 12/13/00
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On December 13, 2000 at 13:35:45, Peter Berger wrote: >I have a question regarding Crafty 17.13's analysis to "A testposition for >chessprograms" posted by >Uri Blass recently ( http://icdchess.com/forums/1/message.shtml?144190 ): > >Test 1 : > >White(1): setboard b7/1q2p2k/3p1p1p/1Pr1nP2/6PP/1rN5/2RKBQ2/2R5 b - - 0 1 >Black(1): search Rd5 >Black(1): analyze >Analyze Mode: type "exit" to terminate. > clearing hash tables > time surplus 0.00 time limit 30.00 (3:00) > nss depth time score variation (1) >starting thread 1 >starting thread 2 >starting thread 3 > > ... > > > 13 3:10 0.87 1. ... Rd5+ 2. Nxd5 Qxd5+ 3. Ke1 Rh3 > 4. Rc3 Rh1+ 5. Bf1 Nd3+ 6. Rxd3 Qxd3 > 7. g5 hxg5 8. hxg5 Qe4+ 9. Kd2 fxg5 > 10. Re1 Qb7 > 13-> 3:10 0.87 1. ... Rd5+ 2. Nxd5 Qxd5+ 3. Ke1 Rh3 > 4. Rc3 Rh1+ 5. Bf1 Nd3+ 6. Rxd3 Qxd3 > 7. g5 hxg5 8. hxg5 Qe4+ 9. Kd2 fxg5 > 10. Re1 Qb7 > 14 7:24 ++ 1. ... Rd5+!! > 14 46:59 2.17 1. ... Rd5+ 2. Nxd5 Qxd5+ 3. Ke1 Rh3 > 4. Rc3 Rh1+ 5. Bf1 Nd3+ 6. Rxd3 Qxd3 > 7. Rd1 Qxb5 8. Qe2 Qxe2+ 9. Kxe2 Rxh4 > 10. Rd4 Rh2+ 11. Ke3 Bc6 > 14-> 46:59 2.17 1. ... Rd5+ 2. Nxd5 Qxd5+ 3. Ke1 Rh3 > 4. Rc3 Rh1+ 5. Bf1 Nd3+ 6. Rxd3 Qxd3 > 7. Rd1 Qxb5 8. Qe2 Qxe2+ 9. Kxe2 Rxh4 > 10. Rd4 Rh2+ 11. Ke3 Bc6 > 15 73:28 2.26 1. ... Rd5+ 2. Nxd5 Qxd5+ 3. Ke1 Rh3 > 4. Rc3 Rh1+ 5. Bf1 Nd3+ 6. Rxd3 Qxd3 > 7. Rd1 Qxb5 8. Qe2 Qxe2+ 9. Kxe2 Rxh4 > 10. Rd4 h5 11. Ra4 Bd5 > 15-> 73:28 2.26 1. ... Rd5+ 2. Nxd5 Qxd5+ 3. Ke1 Rh3 > 4. Rc3 Rh1+ 5. Bf1 Nd3+ 6. Rxd3 Qxd3 > 7. Rd1 Qxb5 8. Qe2 Qxe2+ 9. Kxe2 Rxh4 > 10. Rd4 h5 11. Ra4 Bd5 > >Test 2 : > >White(1): setboard b7/1q2p2k/3p1p1p/1Pr1nP2/6PP/1rN5/2RKBQ2/2R5 b - - 0 1 >Black(1): analyze >Analyze Mode: type "exit" to terminate. > clearing hash tables > time surplus 0.00 time limit 4:20 (4:20) > nss depth time score variation (1) >starting thread 1 >starting thread 2 >starting thread 3 > > ... > > > 13 104:47 0.92 1. ... Kg7 2. h5 Kh7 3. Qf1 Qc7 4. > Qf4 Nc4+ 5. Bxc4 Rxc4 6. Qe3 Rxg4 7. > Qe6 Rg2+ 8. Ke1 Rg1+ 9. Kd2 Rxc1 10. > Rxc1 > 13-> 111:57 0.92 1. ... Kg7 2. h5 Kh7 3. Qf1 Qc7 4. > Qf4 Nc4+ 5. Bxc4 Rxc4 6. Qe3 Rxg4 7. > Qe6 Rg2+ 8. Ke1 Rg1+ 9. Kd2 Rxc1 10. > Rxc1 > 14 246:36 1.20 1. ... Kg7 2. h5 Qc7 3. Qd4 Nc4+ 4. > Bxc4 Rxc4 5. Qe3 Be4 6. Nxe4 Rxc2+ > 7. Rxc2 Qxc2+ 8. Kxc2 Rxe3 9. Nc3 Rg3 > 10. Nd5 Rxg4 11. Nxe7 > 14-> 268:29 1.20 1. ... Kg7 2. h5 Qc7 3. Qd4 Nc4+ 4. > Bxc4 Rxc4 5. Qe3 Be4 6. Nxe4 Rxc2+ > 7. Rxc2 Qxc2+ 8. Kxc2 Rxe3 9. Nc3 Rg3 > 10. Nd5 Rxg4 11. Nxe7 > 15 773:32 1.22 1. ... Kg7 2. Qf1 Rb4 3. Qf2 Nf3+ 4. > Bxf3 Qxf3 5. Qxf3 Bxf3 6. Rg1 Kf7 <HT> > (4) 15-> 876:46 1.22 1. ... Kg7 2. Qf1 Rb4 3. Qf2 Nf3+ 4. > Bxf3 Qxf3 5. Qxf3 Bxf3 6. Rg1 Kf7 <HT> > (3) 16 1129:40 1.32 1. ... Kg7 2. Qf1 Rb4 3. Qf2 Nf3+ 4. > Bxf3 Qxf3 5. Qxf3 Bxf3 6. Rg1 Kf7 7. > g5 hxg5 8. hxg5 fxg5 9. Rxg5 Kf6 10. > Rg3 Rxf5 11. Ke3 > > >Why won't crafty find/choose ... Rd5+ at ply 14 and 15 in Test 2 ? Most likely a null-move issue. If you force it to only search the key move, null-move doesn't influence the search as much. But when you let it search everything, null-move is used to dismiss all the ply-1 moves (except the first one) very quickly...
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