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Subject: Sacrifices of chess programs

Author: Uri Blass

Date: 07:20:37 11/08/01


I define a real sacrifice of chess program as a move that is losing material
based on only material evaluation but is played by the program because the
positional score is bigger than a pawn.

How many real sacrifice are played by programs?

It may be interesting to get information about the average number of real
sacrifice per game by different programs.

I define a sacrifice as something that is seen by only material evaluation as a
mistake and the program need to choose it not because of the fact that the loss
was too deep or because a bug in the search but because of the evaluation
function.

Here is an example of a real sacrifice that part of the programs play(after h4
Nxh4 black is a pawn down) and example of a move that I believe that is simply a
tactical blunder that is too deep for programs to see

Abir Har aven - Uri Blass
[D]rnbqkbnr/ppp1ppp1/8/3p3p/5P2/5NP1/PPPPP2P/RNBQKB1R b KQkq - 0 1

Analysis by Junior 7:

3...h4 4.Nxh4
  ²  (0.32)   Depth: 3   00:00:00
3...g6 4.Nc3
  =  (0.06)   Depth: 3   00:00:00
3...d4 4.Bg2
  =  (-0.01)   Depth: 3   00:00:00
3...c5 4.Nc3
  =  (-0.06)   Depth: 3   00:00:00
3...Nh6 4.Nc3
  =  (-0.09)   Depth: 3   00:00:00
3...Nf6 4.Nc3
  =  (-0.20)   Depth: 3   00:00:00
3...Bf5 4.Nc3
  ³  (-0.34)   Depth: 3   00:00:00
3...Bf5 4.Nh4 Be4 5.Bg2 Bxg2 6.Nxg2
  ³  (-0.26)   Depth: 6   00:00:00
3...Nf6 4.Nc3 Bf5
  ³  (-0.30)   Depth: 6   00:00:00
3...c5 4.Nc3 d4 5.Na4 Qd5
  ³  (-0.39)   Depth: 6   00:00:00  1kN
3...c6 4.c3 Qb6 5.Qa4
  ³  (-0.46)   Depth: 6   00:00:00  2kN
3...Qd6 4.Nc3 Qc5
  ³  (-0.48)   Depth: 6   00:00:00  2kN
3...Qd6 4.d4 Bf5 5.Nh4 Be4 6.Bg2 Bxg2
  ³  (-0.41)   Depth: 9   00:00:00  14kN
3...Qd6 4.c4 dxc4 5.Na3 c3 6.Bg2 Qb6 7.bxc3
  ³  (-0.42)   Depth: 12   00:00:00  170kN
3...h4 4.Bg2 h3 5.Bf1 c6 6.c3 Qb6 7.Qa4
  ³  (-0.58)   Depth: 12   00:00:00  317kN
3...h4 4.Rg1 hxg3 5.Rxg3 Qd6 6.d3 Bf5 7.Bd2
  ³  (-0.54)   Depth: 15   00:00:04  2153kN

(Blass, Tel-aviv 08.11.2001)

Dov Rozenberg - Uri Blass
[D]2r2rk1/p3q1pp/bp6/2bp1p2/4n3/1P2P1P1/PB1N1PBP/1QRR2K1 w - - 0 1

I believe that 23.Nf1 is losing a pawn or a rook for a bishop and a pawn but
programs positional scores are high here and simply hide the picture and I have
not program with only material evaluation to check it.

the analysis is 23.Nf1 Be2 24.Rxd5 Qf7 25.Re5 Rcd8 26.g4 fxg4 27.Rxe4 Qxf2+
28.Kh1 Bf3 29.Bxf3 Qxf3+ 30.Kg1 g3 31.Qc2 gxh2+

In the game my opponent chose 26.Rcxc5

Is there a program with only material evaluation or at least mainly material
evaluation in order to find tactical mistakes or sacrifices in a game and if
there is more than one what is the best program to find material mistakes or
sacrifices?

Uri



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