bob wrote: ↑Tue Oct 29, 2019 6:10 pm
If you do a normal search to depth=24, you get a score and refute all the other moves.
For this to work you have to exclude the move right as its PV at Depth 24 is known, you don't let iteration 24 finish but instead jump directly to analyzing the second best move to Depth 24. You only let the iteration finish on the last move you're interested in (in the case of MultiPV=4, just let iteration 24 complete for the fourth move.)
Okay, let me dig up Rybka Randomizer and actually show what I'm talking about.
[d]rnbqkb1r/pp2pppp/2p2n2/3p4/2PP4/5N2/PP2PPPP/RNBQKB1R w KQkq -
Rybka 2.3.2a MutiPV 4
10 0:03 +0.19 4.Nc3 dxc4 5.e3 Be6 6.Be2 Qd6 7.Ne5 (833.924) 223
10 0:03 +0.16 4.g3 dxc4 5.Bg2 Bf5 6.Ne5 Qa5+ 7.Bd2 Qd8 (697.112) 215
10 0:04 +0.06 4.cxd5 cxd5 5.Nc3 Nc6 6.e3 e6 7.Bd3 Bd6 (934.794) 225
10 0:04 +0.03 4.Qb3 dxc4 5.Qxc4 Be6 6.Qb4 Qb6 7.Qxb6 axb6 8.Nc3 (974.724) 224
-----
11 0:07 +0.17 4.g3 dxc4 5.Bg2 Be6 6.O-O Nbd7 7.Qc2 Nb6 (1.684.360) 231
11 0:08 +0.11 4.cxd5 cxd5 5.Nc3 Nc6 6.Bf4 Ne4 7.Qb3 e6 8.Ne5 (1.873.621) 234
11 0:06 +0.06 4.Nc3 dxc4 5.b3 cxb3 6.Qxb3 Qb6 7.Qa4 Bf5 8.Nh4 Bg4 (1.476.287) 239
11 0:08 -0.04 4.Qb3 dxc4 5.Qxc4 Be6 6.Qb4 Qb6 7.Qxb6 axb6 8.Nc3 Na6 (1.939.444) 233
-----
11 0:07 +0.17 4.g3 dxc4 5.Bg2 Be6 6.O-O Nbd7 7.Qc2 Nb6 (1.684.360) 231
11 0:08 +0.11 4.cxd5 cxd5 5.Nc3 Nc6 6.Bf4 Ne4 7.Qb3 e6 8.Ne5 (1.873.621) 234
11 0:06 +0.06 4.Nc3 dxc4 5.b3 cxb3 6.Qxb3 Qb6 7.Qa4 Bf5 8.Nh4 Bg4 (1.476.287) 239
11 0:11 +0.03 4.Qc2 dxc4 5.e3 Na6 6.Qxc4 Qb6 7.Nc3 Be6 8.Qa4 (2.536.345) 233
-----
11 0:07 +0.17 4.g3 dxc4 5.Bg2 Be6 6.O-O Nbd7 7.Qc2 Nb6 (1.684.360) 231
11 0:08 +0.11 4.cxd5 cxd5 5.Nc3 Nc6 6.Bf4 Ne4 7.Qb3 e6 8.Ne5 (1.873.621) 234
11 0:06 +0.06 4.Nc3 dxc4 5.b3 cxb3 6.Qxb3 Qb6 7.Qa4 Bf5 8.Nh4 Bg4 (1.476.287) 239
11 0:11 +0.05 4.Nbd2 g6 5.e3 Bg7 6.Bd3 Na6 7.Qb3 O-O (2.564.661) 233
-----
12 0:20 +0.16 4.Nc3 dxc4 5.e3 b5 6.Be2 Nbd7 7.O-O e6 8.e4 (4.951.453) 246
12 0:14 +0.14 4.g3 g6 5.Bg2 Bg7 6.O-O O-O 7.c5 b6 8.Nc3 (3.370.906) 233
12 0:17 +0.12 4.cxd5 cxd5 5.Nc3 Nc6 6.g3 g6 7.Bg2 Bg7 8.O-O O-O (3.924.278) 235
12 0:21 0.00 4.Nbd2 g6 5.e3 Bg7 6.Bd3 Na6 7.Qb3 Qb6 8.a3 (5.196.348) 247
-----
12 0:20 +0.16 4.Nc3 dxc4 5.e3 b5 6.Be2 Nbd7 7.O-O e6 8.e4 (4.951.453) 246
12 0:14 +0.14 4.g3 g6 5.Bg2 Bg7 6.O-O O-O 7.c5 b6 8.Nc3 (3.370.906) 233
12 0:17 +0.12 4.cxd5 cxd5 5.Nc3 Nc6 6.g3 g6 7.Bg2 Bg7 8.O-O O-O (3.924.278) 235
12 0:29 +0.08 4.Bd2 dxc4 5.e3 b5 6.b3 cxb3 7.axb3 Bf5 8.Be2 Nbd7 9.O-O (6.876.178) 235
-----
13 0:35 +0.17 4.g3 g6 5.Bg2 Bg7 6.O-O O-O 7.c5 b6 8.cxb6 axb6 9.Nc3 (8.257.481) 235
13 0:43 +0.08 4.Bd2 dxc4 5.e3 b5 6.b3 cxb3 7.axb3 Bf5 8.Nc3 Nbd7 9.Nh4 Be6 (10.053.775) 238
13 0:32 +0.06 4.Nc3 dxc4 5.e3 b5 6.Be2 Nbd7 7.O-O e6 8.e4 b4 (7.455.281) 237
13 0:40 +0.06 4.cxd5 cxd5 5.Nc3 Nc6 6.g3 g6 7.Bg2 Bg7 8.O-O O-O 9.Ne5 (9.597.425) 241
-----
14 0:52 +0.14 4.g3 g6 5.Bg2 Bg7 6.O-O O-O 7.c5 b6 8.cxb6 axb6 9.Nc3 Na6 (12.282.860) 239
14 1:20 +0.12 4.cxd5 cxd5 5.Nc3 Nc6 6.g3 g6 7.Bg2 Bg7 8.O-O O-O 9.Ne5 Bf5 (18.965.898) 242
14 1:14 +0.10 4.Nc3 dxc4 5.e3 b5 6.a4 b4 7.Na2 Be6 8.Nxb4 Qd6 9.Bd2 Ne4 (17.271.681) 238
14 1:09 +0.09 4.Bd2 g6 5.Nc3 Bg7 6.e3 O-O 7.Qb3 Qb6 8.Qxb6 axb6 9.cxd5 cxd5 10.Ne5 Rd8 (16.232.958) 238
-----
15 2:05 +0.15 4.Nc3 dxc4 5.e3 b5 6.a4 b4 7.Na2 Be6 8.Nxb4 Qb6 9.Bd2 a5 10.Nc2 (30.354.456) 248
15 2:19 +0.14 4.Bd2 g6 5.Nc3 Bg7 6.e3 O-O 7.Qb3 Qb6 8.Be2 Bf5 9.Nh4 Be6 (33.447.848) 245
15 1:39 +0.12 4.g3 g6 5.Bg2 Bg7 6.O-O O-O 7.c5 b6 8.cxb6 axb6 9.Nc3 Nbd7 10.Bf4 (23.696.866) 243
15 1:53 +0.12 4.cxd5 cxd5 5.Nc3 Nc6 6.e3 g6 7.Bd3 Bg7 8.O-O O-O 9.Qb3 Na5 10.Qb4 (27.627.821) 248
best move: Nb1-c3 time: 2:31.110 min n/s: 249.141 nodes: 36.765.695
15 is the depth wanted and it finishes it in 2:31.110.
*Clears hash*
*Turns on Randomizer*
*Asks for it to play a move up to Depth 15*
11.00 0:01 +0.27 4.e3 g6 5.Nc3 Bg7 6.Bd3 O-O 7.O-O Na6 (443.856) 312
12.01 0:02 +0.18 4.e3 g6 5.Nc3 Bg7 6.Bd3 O-O 7.O-O Na6 8.cxd5 (619.924) 309
13.01 0:03 +0.21 4.e3 g6 5.Nc3 Bg7 6.Bd3 O-O 7.O-O Na6 8.cxd5 Nxd5 9.Nxd5 Qxd5 10.e4 (976.576) 310
14.01 0:04 +0.17 4.e3 g6 5.Nc3 Bg7 6.Bd3 O-O 7.O-O Na6 8.cxd5 Nxd5 9.Nxd5 Qxd5 10.e4 Qd8 (1.450.919) 309
15.01 0:09 +0.25 4.e3 g6 5.Nc3 Bg7 6.Bd3 O-O 7.O-O Na6 8.cxd5 Nxd5 9.e4 Ndc7 10.Be2 (2.890.333) 303
best move: e2-e3 time: 0:10.594 min n/s: 308.370 nodes: 3.171.942
*Takes back e3, asks for another move*
12.01 0:01 +0.18 4.g3 dxc4 5.Bg2 Be6 6.O-O Na6 7.Ng5 Bg4 8.Qa4 h6 9.Nf3 Qd6 (420.095) 269
13.01 0:03 +0.17 4.g3 dxc4 5.Bg2 Be6 6.O-O Na6 7.Ng5 Bg4 8.Qa4 h6 9.Nf3 Qd6 (852.130) 272
14.01 0:04 +0.15 4.g3 dxc4 5.Bg2 Be6 6.O-O Na6 7.Ng5 Bg4 8.Qa4 h6 9.Nf3 Qd6 (1.218.051) 256
15.01 0:12 +0.08 4.g3 dxc4 5.Bg2 Nbd7 6.O-O Nb6 7.a4 a5 8.Nc3 g6 9.b3 cxb3 10.Qxb3 Bg7 (3.627.472) 301
best move: g2-g3 time: 0:13.250 min n/s: 301.168 nodes: 3.892.838
*Takes back g3, asks for another move*
11.00 0:00 +0.09 4.c5 b6 5.cxb6 axb6 6.Nc3 Bf5 7.Nh4 Be6 8.Bf4 Nbd7 9.Qd3 (210.191) 352
12.01 0:01 +0.06 4.c5 b6 5.cxb6 axb6 6.Nc3 Bf5 7.Nh4 Be6 8.Bf4 Nbd7 9.Qd3 (463.725) 303
12.03 0:02 +0.09 4.Nc3 dxc4 5.Ne5 Be6 6.e4 Nbd7 7.Nxc4 b5 8.Ne3 Nb6 (886.410) 326
13.01 0:06 +0.10 4.Nc3 dxc4 5.Ne5 Be6 6.e4 Nbd7 7.Nxc4 b5 8.Ne3 b4 9.d5 (2.010.872) 332
14.01 0:08 +0.10 4.Nc3 dxc4 5.e3 b5 6.a4 b4 7.Na2 Be6 8.Nxb4 Qd6 9.Bd2 Ne4 (2.917.088) 337
15.01 0:14 +0.09 4.Nc3 dxc4 5.e3 b5 6.a4 b4 7.Na2 Be6 8.Nxb4 Qd6 9.Bd2 Nbd7 10.Ng5 (4.893.954) 344
best move: Nb1-c3 time: 0:17.500 min n/s: 347.260 nodes: 5.924.454
*Takes back Nc3, asks for final move and lets iteration end*
11.00 0:01 +0.08 4.Nbd2 g6 5.e3 Bg7 6.Bd3 O-O 7.Qb3 Na6 8.O-O Qb6 (297.099) 218
12.01 0:03 +0.03 4.Nbd2 g6 5.e3 Bg7 6.Bd3 O-O 7.Qb3 Na6 8.O-O Qb6 (855.970) 270
12.02 0:03 +0.11 4.Bd2 dxc4 5.e3 b5 6.a4 Be6 7.Be2 Qb6 8.O-O Nbd7 9.Qc2 (864.864) 267
13.01 0:03 +0.11 4.Bd2 dxc4 5.e3 b5 6.a4 Be6 7.Be2 Qb6 8.O-O Nbd7 9.Qc2 (872.204) 264
14.01 0:07 +0.09 4.Bd2 dxc4 5.e3 b5 6.a4 Be6 7.Be2 Qb6 8.O-O Nbd7 9.Qc2 (1.956.655) 284
15.01 0:13 +0.07 4.Bd2 dxc4 5.e3 Be6 6.Nc3 Qb6 7.Ne5 Nbd7 8.Nxc4 Qc7 9.a4 O-O-O 10.Be2 (3.713.282) 285
15.03 0:30 +0.08 4.cxd5 cxd5 5.Nc3 Nc6 6.e3 g6 7.Bd3 Bg7 8.O-O O-O 9.Qb3 Na5 10.Qb4 (9.300.487) 312
best move: c4xd5 time: 0:30.532 min n/s: 312.406 nodes: 9.300.498
Lines:
15.01 0:09 +0.25 4.e3 g6 5.Nc3 Bg7 6.Bd3 O-O 7.O-O Na6 8.cxd5 Nxd5 9.e4 Ndc7 10.Be2 (2.890.333) 303
15.01 0:12 +0.08 4.g3 dxc4 5.Bg2 Nbd7 6.O-O Nb6 7.a4 a5 8.Nc3 g6 9.b3 cxb3 10.Qxb3 Bg7 (3.627.472) 301
15.01 0:14 +0.09 4.Nc3 dxc4 5.e3 b5 6.a4 b4 7.Na2 Be6 8.Nxb4 Qd6 9.Bd2 Nbd7 10.Ng5 (4.893.954) 344
15.03 0:30 +0.08 4.cxd5 cxd5 5.Nc3 Nc6 6.e3 g6 7.Bd3 Bg7 8.O-O O-O 9.Qb3 Na5 10.Qb4 (9.300.487) 312
Times:
0:10.594
0:13.250
0:17.500
0:30.532
Total time taken: 71.876 seconds
Difference:
MultiPV=4 took 2:31.110
Excluding the best move took 1:11.876 seconds
Suggested strategy saved 1 minute 20 seconds.
Note:
My last MultiPV change suggestion was a success and made it into Stockfish 10, though that one didn't depend on good hash management...
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