Author: Brian Richardson
Date: 20:27:13 09/12/02
Go up one level in this thread
On September 12, 2002 at 22:56:12, James Swafford wrote: > >I'm (still) working with my hash tables, and having quite a time >with this one. I'm hoping someone can explain this behavior: > >1. In iteration 1, the search returns a score of 15 for move A. >2. Naturally, the iteration 2 search begins with move A. The search > window is set to +/- 1 pawn ==> -85, 115. (Yes, that's wide, > but that's not the point. :) >3. Move A again gets a score of 15 from the depth 2 search. > The search continues, though, and root move B fails high. > Move B is a move that leads to mate in 3 (half moves), so > an extension was triggered (I don't think this is important). When storing the hashed result, do you hash store the depth when probed before extensions? >4. The iteration 2 search is restarted with a wider window of > +/- infinity. >5. Move A immediately gets researched and, after one node, > gets a score of 15 (no problem so far). Shouldn't move B get researched here? >6. Iteration 2 finished, and move A is the pv move. Move B, > the move that caused the fail high earlier, has a _very_ > negative score of -675. And it's supposed to be mate in 3. >7. Steps 2-5 are repeated for iteration 3. >8. Move B gets a score of CHECKMATE-3 (mate in 3), and replaces > move A in the pv. > >This is a hashing issue. If I clear the hash table after failing >high at the root, move B is found at iteration 2 with the proper >score of mate in 3. > >I'm stumped. Can anybody offer an explanation? Search output >below if it'll help. :) > >-- >James > >Problem 1: >r1bq2rk/pp3pbp/2p1p1pQ/7P/3P4/2PB1N2/PP3PPR/2KR4 w - - h6h7; > >parsing: h6h7...done. >correct move(s): h6h7 >FW Dpth Nd Cnt CSecs Score PV Line > 1& -> 15 0 -570 h6g7 g8g7 > 1& -> 216 5 10 h6g5 g6h5 > 1& -> 589 5 15 h6f4 d8e8 >before sort... >Move list: >h6g7(-570) h6g6(-675) h6g5(10) h6f4(15) h6e3(10) h6d2(10) h6h7(-675) h5g6(-580) >d4d5(-880) c3c4(-880) d3c4(-885) d3b5(-885) d3a6(-885) d3e2(-885) d3f1(-885) >d3c2(-885) d3b1(-885) d3e4(-885) d3f5(-885) d3g6(-775) f3e5(-875) f3g5(-885) >f3h4(-895) f3d2(-885) f3e1(-895) f3g1(-900) a2a3(-880) a2a4(-875) b2b3(-880) >b2b4(-875) g2g3(-880) g2g4(-875) h2h1(-885) h2h3(-885) h2h4(-885) c1c2(-770) >c1d2(-885) c1b1(-770) d1e1(-885) d1f1(-885) d1g1(-885) d1h1(-885) d1d2(-885) > > 1 -> 2299 16 15 h6f4 d8e8 > 2& -> 3373 16 15 h6f4 d8f6 f4f6 > 2& -> 6558 27 +++ h6h7 > 2& -> 6559 27 15 h6f4 d8f6 >before sort... >Move list: >h6f4(15) h6g5(5) h6e3(10) h6d2(10) h6g7(-555) h5g6(-85) h6g6(-670) h6h7(-675) >c1c2(-85) c1b1(-85) d3g6(-1100) f3e5(-880) a2a4(-880) b2b4(-880) g2g4(-880) >d4d5(-895) c3c4(-885) a2a3(-885) b2b3(-885) g2g3(-885) d3c4(-890) d3b5(-1195) >d3a6(-1180) d3e2(-890) d3f1(-890) d3c2(-890) d3b1(-890) d3e4(-890) d3f5(-1190) >f3g5(-985) f3d2(-885) h2h1(-885) h2h3(-885) h2h4(-885) c1d2(-890) d1e1(-885) >d1f1(-885) d1g1(-885) d1h1(-885) d1d2(-885) f3h4(-985) f3e1(-900) f3g1(-905) > > 2 -> 26715 60 15 h6f4 d8f6 > 3& -> 31482 66 20 h6f4 g6h5 f4f7 g7h6 > 3& -> 73074 115 +++ h6h7 > 3& -> 73075 115 20 h6f4 g6h5 > 3& -> 97128 148 59997 h6h7 h8h7 h5g6 >before sort... >Move list: >h6f4(20) h6e3(0) h6d2(0) h6g5(5) h5g6(-580) c1c2(-650) c1b1(-650) h6g7(-555) >h6g6(-660) h6h7(59997) f3e5(-880) a2a4(-885) b2b4(-885) g2g4(-885) c3c4(-890) >a2a3(-890) b2b3(-890) g2g3(-890) f3d2(-890) h2h1(-895) h2h3(-895) h2h4(-895) >d1e1(-895) d1f1(-895) d1g1(-895) d1h1(-890) d1d2(-885) d3c4(-895) d3e2(-895) >d3f1(-895) d3c2(-895) d3b1(-895) d3e4(-895) c1d2(-895) d4d5(-895) f3e1(-905) >f3g1(-910) f3g5(-985) f3h4(-995) d3g6(-1100) d3a6(-1180) d3f5(-1185) d3b5(-1195) > > 3 -> 205158 258 59997 h6h7 h8h7 h5g6 > >nodes -> total: 205158; nps: 79518; csecs: 258 > int: 41013; frontier: 75894; quiesce: 164145 >hash -> fh: 1286 (3); fl: 170 (0); ex: 22592 (55) > hash mvs played: 4837 >mv ord -> fh 1st mv: 94(12822 cuts, 12147 1st mv); avg bf: 8.650 >ext. -> one rep: 444; pp: 351; recap: 9114 > >move h6h7 >CORRECT
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