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Subject: Pawn patterns and evaluation of positional advantage

Author: Uri Zlatnik

Date: 15:25:06 12/21/04


The recognition of winning pawn structure is one of the problems of chess
softwares (including top ones like Junior 9 and Shredder 8).

Many times there is a sound sacrifice (usually winning) which the program fails
to "see" immediately. This will take Kasparov not more than 1 minute to figure
out.

For example take the game of Kuzmin-Grospeter, Kusadasi 1990:

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be2 e5 7. Nb3 Be7 8. 0-0
0-0 9. Kh1 b5 10. Nd5! Nxd5 11. Qxd5 Ra7 12. Be3 Be6 13. Qd1 Rd7 14. a4 b4 15.
f4! Qc7? 16. f5! Bc4 17. Bxc4 Qxc4

At first glance we notice that Black is attacking an e-pawn which is difficult
to defend comfortably (18. Qf3 Qxc2). Then we might appreciate that white has a
clear positional advantage thanks to the pawn structure: The d5-hole gives White
an excellent outpost and the f5-pawn gives him the basis for kingside attack.

But protecting e4 through normal means will vaporize those advantages (18. Qd3?
Qxd3 19. cxd3 Rc8 or 18. Nd2 Qc6 and 19... d5). Moreover, White understands that
whatever advantage the structure offers him will be wiped out once Black
activates his poorly placed pieces (... Rc7 and ...Nd7-f6). Putting it all
together, White concludes his advantage is fleeting and he must use it
immediately regardless of material consequences. And so he finds:

18 f6! Bxf6 19. Rxf6! gxf6 20. Qg4+

The attractive 20. Bh6, threatening 21. Qg4+ and mates, would allow 20 ...
Qxe4!.

20... Kh8 21. Qh4 Qe6

Black cannot allow 22. Qxf6+ and 23. Bh6, with mate to follow on g7. But now...

22. Nd4!! Qe7

After 22 ... exd4 23 Bxd4 Black cannot defend against Bxf6+ e.g., 23 ... Kg7 24
Qg5+)

23. Nf5 Qe6 24. Rf1 d5

At last, desperate attempt to get his pieces into defensive (...Rd6, ... Nd7)
action.

25 Ng7! Qe7 Or 25 ... Kxg7 26 Bh6+ Kh8 27. Bxf8, threatening 28. Qh6

26. Bc5! Qxc5 27. Nh5 Resigns




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