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Subject: Re: position, trapped rook

Author: Richard Pijl

Date: 05:53:36 06/09/04

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On June 09, 2004 at 06:12:24, Stan Arts wrote:

>Yesterday, in the evening took my tabletop chesscomputer outside for a quick
>game.
>
>This position came on the board.
>
>[D]r4rk1/1Rp3pp/2pq4/p2p1p2/Q1nP4/2P1P3/P4PPP/2B2RK1 w - a6 0 18
>
>Here, it's easy as a human to see I can trap the rook with the knight, and then
>win the quality with my queen if white doesn't move it away first. Is there any
>program that can see that fast as well? Probably by evaluation, (For instance
>something like almost no mobility left and surrounded/paths stopped by opponent
>pieces fairly close by) because by calculation it's very deep and takes a long
>time.
>
>Neurosis does not have such code (yet) and needs depth 12 to see the rook will
>be in trouble after playing Rd1, and then finds Qb3 that probably delays the
>trouble till depth 13 or 14. The other program's I tried, seem to have the same
>trouble and need similair depths.

White is probably already in trouble, as black has positioned its knight well,
and white has a big pawn for a bishop.
However, collecting the exchange will cost black its strong knight (+ probably a
pawn) and black will need to defend c7 too. That will give white some time to
improve its bishop and sac the exchange possibly afterwards.

From the diagram position the Baron (on a Xeon 2.8Ghz, 100Mb hash) likes to play
Qb3, but with a slowly deteriorating score:
 ply       time        nodes   score  pv
  5( 9).   0:00.08     18450   +0.31  Qa4-c2 Ra8-c8 Rf1-e1 Qd6-g6 Kg1-h1
  6(10)&   0:00.11     28739   +0.23  Qa4-c2 Ra8-c8 Bc1-d2 Nc4-a3 Qc2-b2 Na3-c4
  6(12).   0:00.28     81024   +0.23  Qa4-c2 Ra8-c8 Bc1-d2 Nc4-a3 Qc2-b2 Na3-c4
  7(13)&   0:00.47    139938   +0.14  Qa4-c2 Ra8-a6 Rf1-e1 Ra6-b6 Rb7-a7 c6-c5
                                      Qc2-e2
  7(14).   0:00.69    206772   +0.14  Qa4-c2 Ra8-a6 Rf1-e1 Ra6-b6 Rb7-a7 c6-c5
                                      Qc2-e2
  8(15)&   0:01.13    346358   +0.12  Qa4-c2 Ra8-a6 Rf1-d1 c6-c5 d4xc5 Qd6xc5
                                      Rd1-d4 Ra6-b6 Rb7-a7
  8(15).   0:02.19    681149   +0.12  Qa4-c2 Ra8-a6 Rf1-d1 c6-c5 d4xc5 Qd6xc5
                                      Rd1-d4 Ra6-b6 Rb7-a7
  9(17)&   0:05.24   1637724   -0.06  Qa4-c2 Qd6-d7 Qc2-b1 Qd7-c8 Rb7-b3 Ra8-b8
                                      Rf1-e1 Rb8-b6 Qb1-c2
  9(17).   0:08.80   2770732   -0.06  Qa4-c2 Qd6-d7 Qc2-b1 Qd7-c8 Rb7-b3 Ra8-b8
                                      Rf1-e1 Rb8-b6 Qb1-c2
 10(17)&   0:13.11   4229633   -0.14  Qa4-c2 Qd6-d7 Rf1-e1 Rf8-b8 Rb7-b3 Rb8-b6
                                      f2-f3 Ra8-b8 e3-e4 Qd7-e6
 10(18).   0:22.95   7337142   -0.14  Qa4-c2 Qd6-d7 Rf1-e1 Rf8-b8 Rb7-b3 Rb8-b6
                                      f2-f3 Ra8-b8 e3-e4 Qd7-e6
 11(21)>   1:00.30  19033806   -0.48  Qa4-b3
 11(21)&   1:20.59  25154423   -0.31  Qa4-b3 Qd6-d8 Qb3-a4 Rf8-f6 Rb7-b1 Rf6-g6
                                      Qa4-c2 Qd8-g5 g2-g3 Ra8-c8 Rb1-b7 Qg5-h5
 11(21).   2:00.44  37290479   -0.31  Qa4-b3 Qd6-d8 Qb3-a4 Rf8-f6 Rb7-b1 Rf6-g6
                                      Qa4-c2 Qd8-g5 g2-g3 Ra8-c8 Rb1-b7 Qg5-h5
 12(20)&   2:24.66  45005721   -0.31  Qa4-b3 Qd6-d8 Qb3-a4 Rf8-f6 Rb7-b1 Rf6-g6
                                      Qa4-c2 Qd8-g5 g2-g3 Ra8-c8 Rb1-b7 Qg5-h5
 12(22).   4:10.07  77015560   -0.31  Qa4-b3 Qd6-d8 Qb3-a4 Rf8-f6 Rb7-b1 Rf6-g6
                                      Qa4-c2 Qd8-g5 g2-g3 Ra8-c8 Rb1-b7 Qg5-h5
 13(24)&   5:55.42 109109378   -0.39  Qa4-b3 Ra8-a6 Rb7-b8 Ra6-b6 Rb8xf8 Qd6xf8
                                      Qb3-c2 Rb6-b8 Kg1-h1 Qf8-f6 Rf1-e1
(Kg8-h8)
                                      (a2-a4) (Qf6-g6)

Qc2 is clearly not the move to play here. After forcing Qc2 the Baron gives
positive scores for black and indicates that white has to sac a pawn.

 ply       time        nodes   score  pv
  5( 9).   0:00.05     16593   -0.23  Ra8-c8 Bc1-d2 Nc4-a3 Qc2-b2 Na3-c4
  6( 9)&   0:00.09     28275   -0.28  Ra8-c8 Rf1-e1 c6-c5 Qc2-b3 Rf8-e8 Qb3-b1
  6(11)&   0:00.39    113502   -0.14  Ra8-a6 Rf1-e1 Ra6-b6 Rb7-a7 c6-c5 Qc2-e2
  6(11).   0:00.44    127303   -0.14  Ra8-a6 Rf1-e1 Ra6-b6 Rb7-a7 c6-c5 Qc2-e2
  7(14)&   0:00.63    186885   -0.12  Ra8-a6 Rf1-d1 Ra6-b6 Rb7-a7 c6-c5 d4xc5
                                      Qd6xc5 Rd1-d4
  7(14).   0:00.78    240389   -0.12  Ra8-a6 Rf1-d1 Ra6-b6 Rb7-a7 c6-c5 d4xc5
                                      Qd6xc5 Rd1-d4
  8(16)&   0:01.77    524177   -0.06  Ra8-a6 Rf1-e1 c6-c5 a2-a4 Ra6-b6 Rb7-a7
                                      (Rb6-b8) (Qc2-e2)
  8(16)&   0:03.36   1032479   +0.06  Qd6-d7 Qc2-b1 Qd7-c8 Rb7-b3 Ra8-b8 Rf1-e1
                                      Rb8-b6 Qb1-c2
  8(16).   0:03.53   1086410   +0.06  Qd6-d7 Qc2-b1 Qd7-c8 Rb7-b3 Ra8-b8 Rf1-e1
                                      Rb8-b6 Qb1-c2
  9(17)&   0:06.52   2089281   +0.10  Qd6-d7 Qc2-b1 Rf8-c8 Qb1-c2 Nc4-d6 Rb7-b1
                                      Nd6-e4 Rb1-b7 Ra8-b8
  9(17).   0:08.41   2699565   +0.10  Qd6-d7 Qc2-b1 Rf8-c8 Qb1-c2 Nc4-d6 Rb7-b1
                                      Nd6-e4 Rb1-b7 Ra8-b8
 10(17)&   0:14.38   4656662   +0.11  Qd6-d7 Rb7-b3 Ra8-b8 Rf1-e1 Qd7-e6 Bc1-a3
                                      Rb8xb3 Qc2xb3 Rf8-c8 Ba3-c5 Qe6-e4
 10(19).   0:20.00   6464612   +0.11  Qd6-d7 Rb7-b3 Ra8-b8 Rf1-e1 Qd7-e6 Bc1-a3
                                      Rb8xb3 Qc2xb3 Rf8-c8 Ba3-c5 Qe6-e4
 11(20)&   0:39.73  12914215   +0.13  Qd6-d7 Rb7-b3 Rf8-e8 Rf1-e1 Ra8-b8 (f2-f3)

                                      (Qd7-f7) (e3-e4) (f5xe4) (f3xe4) (Rb8xb3)
(a2xb3)
 11(21)+   1:39.70  31092311   +0.46  Nc4-b6 (Qc2-b3) (Qd6-d8) (c3-c4) (d5xc4) (
Qb3-b1)
                                      (Qd8-c8) (Bc1-a3) (Qc8xb7) (h2-h4)
 11(21)&   2:10.97  40381848   +0.64  Nc4-b6 e3-e4 f5xe4 Qc2-e2 c6-c5 Qe2-b5
                                      c5xd4 c3xd4 a5-a4 Bc1-g5 Rf8-b8 Rb7xb8
                                      Ra8xb8
 11(21).   2:11.84  40652091   +0.64  Nc4-b6 e3-e4 f5xe4 Qc2-e2 c6-c5 Qe2-b5
                                      c5xd4 c3xd4 a5-a4 Bc1-g5 Rf8-b8 Rb7xb8
                                      Ra8xb8
 12(22)&   4:38.67  84334878   +0.76  Nc4-b6 c3-c4 Nb6xc4 Qc2-b3 Ra8-a6 Qb3-d3
                                      Ra6-b6 Rb7-a7 Rb6-b5 Qd3-c2 c6-c5 Rf1-e1
 12(22).   4:45.75  86478575   +0.76  Nc4-b6 c3-c4 Nb6xc4 Qc2-b3 Ra8-a6 Qb3-d3
                                      Ra6-b6 Rb7-a7 Rb6-b5 Qd3-c2 c6-c5 Rf1-e1
 13(25)&  10:27.23 186476945   +0.80  Nc4-b6 c3-c4 Nb6xc4 Qc2-d3 Qd6-d7 Bc1-a3
                                      Rf8-b8 Rf1-b1 Qd7-c8 Rb7-b3 Rb8xb3 Qd3xb3
                                      Qc8-e6
Richard.
>
>Neurosis's output. (One hour on my slow PIII-550 48mb hash, speculative 1)
>
>Legal moves: 32   Static score: 47
>Ply Score Time     Nodes      Best move and expected line
>------------------------------------------------------------
>2   47    0        933        Qb3 c5
>3   48    0        1519       Qb3 c5 Bb2
>4   44    6        4309       Qb3 a4 Qc2 c5
>4   48    17       7369       Qc2 c5 Bb2 Nxb2
>5   39    39       20530      Qc2 Ra8-e8 Rd1 c5 Bb2
>6   32    121      70311      Qc2 c5 Bd2 cxd4 cxd4 c5
>7   23    429      240785     Qc2 c5 Re1 Qc6 Rb3 cxd4 cxd4
>7   24    511      291178     Qb3 < + > c5 Qb5 Rf6
>7   30    561      320674     Qb3 c5 Qb5 c6 Qxc5 Qxc5 dxc5
>8   17    1324     786007     Qb3 Ra6 Qc2 Rb6 Ra7 c5 Bd2 Rb2 Ra1
>8   18    1401     836391     Qc2 < + > c5 Re1 Qc6 Rb3 cxd4 cxd4
>8   18    1555     918079     Qc2 c5 Re1 Qc6 Bb2 Nd2 g4 Ra8-d8
>8   19    2236     1328063    Rd1 < + > Ra8-b8 Qb3 Rxb7 Qxb7 Rf7
>8   20    2340     1389702    Rd1 Ra8-b8 Qb3 a4 Qb1 Rxb7 Qxb7 Re8
>9   21    5663     3310854    Rd1 Ra8-b8 Rb3 Nb6 Qxa5 Nc4 Qc5 Qxc5 dxc5
>10  21    17780    10881418   Rd1 Ra8-b8 Qb3 Rxb7 Qxb7 Rd8 Bb2 c5 Rb1 Nxb2
>11  21    52542    33090279   Rd1 Ra8-b8 Qb3 Rxb7 Qxb7 Rd8 Qb1 Qd7 Qb3 c5 dxc5
>Bb2
>12  -31   163612   100323049  Rd1 < - > Nb6 Qb3 Rf7 Qa3 Qd8 Qc5 Rf6 Rxc7 Qxc7
>Qxb6 Qxb6
>12  -31   171181   104500716  Rd1 Nb6 Rxb6 cxb6 Ba3 c5 dxc5 bxc5 c4 Qb6 cxd5
>Ra8-d8
>12  -30   210222   125003013  Qb3 < + > Ra6 Qc2 Rb6 Ra7 c5 dxc5 Qxc5 f3 Qd3
>12  5     322072   194423290  Qb3 c5 Rd1 a4 Qb1 cxd4 cxd4 Na5 Rb5 c6 Qb4 Qxb4
>Total nodes:217936078 n/sec:60600  (Q-nodes:38% max depth:31)
>
>Greetings Stan
>
>[Date "2004.06.08"]
>[White "Saitek turbo advanced trainer mode d6 - 45 minutes game"]
>[Black "Me"]
>
>1. Nf3 Nf6 2. d4 d5 3. c4 e6 4. Nc3 Bb4 5. cxd5 exd5 6. Qa4+ Nc6 7. e3 Ne4
>8. Bb5 Bd7 9. Qb3 Nd6 10. Bxc6 Bxc3+ 11. bxc3 Bxc6 12. Ne5 O-O 13. Nxc6
>bxc6 14. O-O Nc4 15. Qa4 Qd6 16. Rb1 f5 17. Rb7 a5 18. Qc2 Nb6 19. Bb2 c5
>20. dxc5 Qxc5 21. c4 Qc6 22. Qc3 Rf7 23. Rxb6 cxb6 24. cxd5 Qxd5 25. a3 Rf6
>26. Rc1 Rg6 27. g3 Rf8 28. h3 Qd6 29. Kf1
>(my time was running out, and was time for coffee)



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