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Subject: Quiescence Explosion

Author: David Rasmussen

Date: 01:43:16 11/26/02


[D]r4rk1/1p1n1pp1/1bq1bn1p/p1pp4/2P2B2/1NNP2P1/PPQ2PBP/R4RK1 w - - 0 19

Chezzz encountered this position in a game. This position, and some immediately
before and after it, made Chezzz go nuts in quiescence search:

time         nodes depth    score  pv
00:00:00.14   52kn 02/02/16 ---------------------------------------------------
00:00:00.14   53kn 03/03/08 +0.055 19. Nb5 a4 20. Nd2
00:00:00.17   66kn 03/03/12 +0.100 19. Rae1 Rae8 20. Nb5
00:00:00.25   88kn 03/04/14 ---------------------------------------------------
00:00:01.37  631kn 04/04/16 +0.205 19. Rae1 a4 20. cxd5 Nxd5
                                   21. Nxd5 Bxd5
00:00:01.78  804kn 04/04/16 ---------------------------------------------------
00:00:02.08  953kn 05/06/16 +0.205 19. Rae1 a4 20. cxd5 Nxd5
                                   21. Nxd5 Bxd5
00:00:02.59 1191kn 05/06/16 +0.277 19. Rfe1 a4 20. Nd2 Rfe8
                                   21. cxd5 Nxd5 22. Bxd5 Bxd5
                                   23. Rxe8+ Rxe8 24. Qxa4 Qxa4
                                   25. Nxa4
00:00:04.14 2020kn 05/06/18 +0.410 19. Qd2 Rfe8 20. Rae1 Red8
                                   21. Qe3
00:00:04.20 2040kn 05/06/18 ---------------------------------------------------
00:00:06.00 3083kn 06/08/18 +0.370 19. Qd2 Rfe8 20. Rae1 Rec8
                                   21. Qe3 Bc7
00:00:07.39 3728kn 06/08/19 ---------------------------------------------------
00:00:11.06 5684kn 07/10/21 +0.483 19. Qd2 Rfe8 20. Rae1 Kf8
                                   21. cxd5 Nxd5 22. Nxd5 Bxd5
                                   23. Rxe8+ Kxe8
00:00:12.47 6313kn 07/10/21 ---------------------------------------------------
00:00:28.12   14Mn 08/11/22   6/48 19. Rae1

        Time used: 00:00:30.00
        nps: 497701     nodes: 14936023 Q-nodes: 14513023 (97%)
        move order: 88%
        hash probes: 112554     hash hits: 26981 (23%)  hash usage: 2%
        pawn hash probes: 14816435      pawn hash hits: 14807848 (99%)
        EGTB probes: 0  EGTB hits: 0 (0%)

97% Q-nodes!!
In the other positions near this, it was the same. 97-98%. I don't have the most
brilliant Q-search, but it's not totally naive either. I don't do checks, and I
use SEE to order moves and to throw out moves that won't bring the score up
close to alpha. In usual middlegames, I see percentages of 10%-40%.

So how do your engines do in this positions?
What can be done to lower this number?

/David



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