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Subject: Re: Some Tiger Move Examples

Author: Peter McKenzie

Date: 20:34:02 11/18/99

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Thanks for an interesting post.  I always like it when people put some thought
into analysing actual chess positions and the play that results from them.

Christophe, how about posting scores from Tiger?

I have taken a bried look at these positions and quickly run them on LambChop
for about 60sec on a PII 366mhz.  Comments below:

On November 18, 1999 at 17:33:57, Howard Exner wrote:

>Here are a few examples of nice moves made by Tiger. Perhaps other programs make
>these moves also.
>
>1. Of course in this example white can play anything and win but Tiger chooses
>Qxf7.
>Here Tiger readily enters an endgame with the move Qxf7. This is exactly how any
>strong human would play. Most programs would most likely move the Queen. It is
>for me at least, an indicator that something unique is going on with Tiger's
>endgame eval. If it plays a move like Qxf7
>maybe it knows something about liquidating into completely won endgames.
>
>8/p2k1r2/1p2bQ2/3p4/8/1P4P1/1PP2R1P/6K1 w - - id Chess Tiger - Goldbar; bm f6f7;

Yes, Qxf7 is the human move and a nice way to tidy up the game.  My program kept
switching between Qxf7, Qd4 and Qe5, in the end choosing Qe5 with a +10.9 score.
Would be nice if it played Qxf7, but I'm not too worried when it sees such a big
score.  Food for though though.

>
>2. This game illustrates an excellent liquidation into a won endgame. Noteworthy
>are the
>two rook captures on f6. The move Bh3 is one of the nicest examples I've seen of
>a program
>swapping down into an easily won endgame. Here are the three moves and the
>entire game.
>
>1rb2rk1/p1q2ppp/2nb1n2/2p1p3/4P3/1PNPN1P1/1BPQ2BP/R4RK1 w - - id Chess Tiger
>12.0 K6 - Nimzo '99 P200MMX; bm f1f6;

Initially Chop liked Nd5, but changed to Rxf6 after 6sec.  Stayed with that move
for the 60sec.  Score +.98 pawns after 9ply search.

>1r1q1rk1/p3bp1p/2n1bp1Q/2pNp3/4P3/1PNP2P1/1BP3BP/5RK1 w - - id Chess Tiger 12.0
>K6 - Nimzo '99 P200MMX; bm f1f6;

Switching between Nxf6 and Rxf6 for a while.  Locked onto Rxf6 after 7sec.
Score +1.31 after 8ply.

>2r2rk1/p2qbp1p/2n1bR1Q/1NpNp3/4P3/1P1P2P1/1BP3BP/6K1 w - - id Chess Tiger 12.0
>K6 - Nimzo '99 P200MMX; bm g2h3;

I don't get Bh3 here, I'll have to take a longer look at it when I get home.
I stay with Qg5+ from ply 2.
I let it run for couple of min, the score was +3.74 after 9ply.
PV starts with 1.Qg5+ Kh8 2.Bxe5+ Nxe5 3.Qxe5+ Kg8 4.Bh3
Does this transpose?
Perhaps an improvement over Bh3 !?

>
>[Event "SSDF Game 40/2"]
>[Site "Hans C."]
>[Date "1999.11.07"]
>[Round "22"]
>[White "Chess Tiger 12.0 K6450"]
>[Black "Nimzo '99 P200MMX"]
>[Result "1-0"]
>[WhiteElo "?"]
>[BlackElo "?"]
>[ECO "B24"]
>
>1. e4 c5 2. Nc3 Nc6 3. g3 Rb8 4. Bg2 b5 5. Nge2 b4 6. Nd5 e6 7. Ne3 Nf6
>8. d3 Be7 9. a3 bxa3 10. b3 O-O 11. O-O d6 12. Bxa3 e5 13. Bb2 Qc7 14.
>f4 Bd7 15. fxe5 dxe5 16. Nc3 Bd6 17. Qd2 Bc8 18. Rxf6 gxf6 19. Ned5 Qd8
>20. Qh6 Be7 21. Rf1 Be6 22. Rxf6 Rc8 23. Nb5 Qd7 24. Bh3 Bxh3 25. Qg5+
>Kh8 26. Bxe5 Nxe5 27. Qxe5 Bxf6 28. Qxf6+ Kg8 29. Ne7+ Qxe7 30. Qxe7 f6
>31. Nxa7 Rf7 32. Nxc8 Rxe7 33. Nxe7+ Kf7 34. Nd5 Be6 35. Kf2 f5 36. Ke3
>h6 37. Nf4 Bd7 38. e5 Bc6 39. e6+ Ke7 40. c4 1-0
>
>3. A nice move exploiting some of black's kingside weaknesses.
>
>1rb1r1k1/pp3p1p/2np2p1/q1p5/3bPB2/2NP1BP1/PPPQ1R1P/5RK1 w - - id Chess Tiger
>12.0 K6 - Nimzo '99 P200MMX; bm f4d6;

Chop locks on to Bxd6 straight away, and holds for 60sec.
Score is only about +.26 though.

>
>4. Nxc5 leads to active piece play for white. The next few moves went 1 ... Nxf1
>2. Kxf1 Bc8
>and black's position is extremely cramped. Whether or not Nxc5 is the best move
>is debatable(black's move Bc8 may not be the best defense)but it appears to
>reveal an awareness of how the relative value of pieces change depending on
>position.
>
>r2q1rk1/pp1b1pbp/2n1p1p1/2p1P3/P2pNP2/1P1PnNP1/2PQ2BP/R1B2RK1 w - - id Chess
>Tiger 12.0 do - Shredder 2 P200MMX ; bm e4c5;

Interesting.  Chop wants to move its rook, switching between Re1 and Rf2 with a
slight plus to white.  I have a later version at home with better outpost
scoring that might choose differently here.  I doubt it will sac the change
though.

cheers,
Peter



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