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Subject: Re: Blocked pieces

Author: Steffen Jakob

Date: 12:37:49 06/21/00

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On June 21, 2000 at 08:30:59, Enrique Irazoqui wrote:

>[D]1r6/1pb1k1p1/4p2p/1p1p4/3Pp2P/1R2P1PB/1P2P1K1/8 b - - 0 1
>
>Yesterday I looked at this position that reveals once again how much trouble
>programs have in recognizing the importance of blocked pieces. Some programs
>pick and drop 1...b4, but none of them realize that the blocked rook is out of
>the game until the search makes them see the consequences many hours later. The
>evaluation at the initial position or after 1...b4 2.Rxb4 b5 3.Rb3 b4 is almost
>the same. It takes 61 minutes for F6a and 335 minutes for Tiger to pick b4, and
>much, much longer to fail high.
>
>[Event "Biel"]
>[Site "?"]
>[Date "1977.??.??"]
>[Round "?"]
>[White "Andersson"]
>[Black "Torre"]
>[Result "0-1"]
>[SetUp "1"]
>[FEN "1r6/1pb1k1p1/4p2p/1p1p4/3Pp2P/1R2P1PB/1P2P1K1/8 b - - 0 1"]
>[PlyCount "7"]
>[EventDate "1997.??.??"]
>
>1... b4 $3 2. Rxb4 b5 $1 3. h5 (3. Rb3 b4 {
>/\...Bd6, Re8 (>< e6), Kd8-c7-...-c4 -+; >< g3}) 3... Bd6 4. Rb3 b4 $1 $19 {
>>< Rb3, g3; /\ 5...Re8 (>< e6), 6... Kd8-c7-...-c4 -+ Andersson-Torre/Biel1977}
>0-1
>
>n-Torre/Biel1977}
>0-1

Hossa knows about paralyzed rooks and queens and therefore he finds the solution
- even for the right reason. Unfortunately my current infrastructure is not very
good for this eval features and this is one of the reasons why my program is
rather slow. I really hope that my rewrite will speed up especially the
queen/rook evaluation dramatically. :-)

  +---+---+---+---+---+---+---+---+
8 |   |=R=|   |   |   |   |   |   |
  +---+---+---+---+---+---+---+---+    Black: Hossa v1.81 (C) (0)
7 |   |=P=|=B=|   |=K=|   |=P=|   |
  +---+---+---+---+---+---+---+---+    Black material: 15.31
6 |   |   |   |   |=P=|   |   |=P=|
  +---+---+---+---+---+---+---+---+
5 |   |=P=|   |=P=|   |   |   |   |
  +---+---+---+---+---+---+---+---+    Black to move
4 |   |   |   | P |=P=|   |   | P |
  +---+---+---+---+---+---+---+---+
3 |   | R |   |   | P |   | P | B |
  +---+---+---+---+---+---+---+---+    White material: 14.31
2 |   | P |   |   | P |   | K |   |
  +---+---+---+---+---+---+---+---+    White: opponent (0)
1 |   |   |   |   |   |   |   |   |
  +---+---+---+---+---+---+---+---+
    a   b   c   d   e   f   g   h

 depth   value    time    nodes pv
    1     0.17    0.00        3 1... b8a8 2.b3xb5
  2/1     0.26    0.00        7 1... c7d6 2.b3xb5
   <1>    0.26    0.00       64 1... c7d6 2.b3xb5
    2     0.26    0.01       85 1... c7d6 2.b3xb5
   <2>    0.26    0.01      192 1... c7d6 2.b3xb5
    3     0.38    0.01      316 1... c7d6 2.b3xb5 g6
   <3>    0.38    0.03     1117 1... c7d6 2.b3xb5 g6
    4     0.08    0.04     1386 1... c7d6 2.b3xb5 g6 3.b5a5
  2/4     0.09    0.05     1793 1... b8a8 2.b3xb5 b6 3.g2f2
  3/4     0.21    0.06     2200 1... b8f8 2.b3xb5 b6 3.b5b3
   <4>    0.21    0.10     4435 1... b8f8 2.b3xb5 b6 3.b5b3
    5     0.37    0.13     6109 1... b8f8 2.b3xb5 b6 3.h3g4 g6
  9/5     0.47    0.19     9095 1... c7a5 2.b3xb5 a5d2 3.g2f2 b8f8
                                4.f2g2
   <5>    0.47    0.21    10512 1... c7a5 2.b3xb5 a5d2 3.g2f2 b8f8
                                4.f2g2
    6     0.27    0.24    12548 1... c7a5 2.b3xb5 a5d2 3.b5b6 d2xe3
                                4.b6xe6 e7f7
   <6>    0.27    0.46    25559 1... c7a5 2.b3xb5 a5d2 3.b5b6 d2xe3
                                4.b6xe6 e7f7
    7     0.50    0.53    30529 1... c7a5 2.b3xb5 a5d2 3.g2f2 g6
                                4.b5b6 b8f8 5.f2g2
   <7>    0.50    0.84    53261 1... c7a5 2.b3xb5 a5d2 3.g2f2 g6
                                4.b5b6 b8f8 5.f2g2
    8     0.23    1.06    67973 1... c7a5 2.b3xb5 a5d2 3.b5b3 g6
                                4.b3a3 b8f8 5.h3g4
! 2/8     0.95    1.65   106338 1... b4 2.b3xb4 b5 3.h3g4 c7d6
                                4.b4b3 b4 5.g2f2
!  <8>    0.95    1.67   108356 1... b4 2.b3xb4 b5 3.h3g4 c7d6
                                4.b4b3 b4 5.g2f2
    9     1.22    1.96   129285 1... b4 2.b3xb4 b5 3.h3g4 c7d6
                                4.b4b3 b4 5.g2h3 b8f8
   <9>    1.22    2.04   135598 1... b4 2.b3xb4 b5 3.h3g4 c7d6
                                4.b4b3 b4 5.g2h3 b8f8

Best wishes,
Steffen.



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