Computer Chess Club Archives


Search

Terms

Messages

Subject: Fritz 6 misses a mate in three moves

Author: Dadi Jonsson

Date: 16:18:06 12/11/99


The Allwermann incident has been discussed here recently. On a related note I
have been assigned to the task of determining if one of the players in the
Icelandic Internet Chess Championship used a chess program. The problem of
determining this is very interesting, but of course it is not obvious how one
can *prove* or *refute* such a theory. (Any ideas are welcome!)

I have gone through many games from the tournament using several different
methods with the help of Fritz 6. The following game was quite interesting with
regard to Fritz's evaluation:

[Event "Icelandic Internet Championship"]
[Site "ICE, Reykjavik, Iceland"]
[Date "1999.11.07"]
[Round "8"]
[White "Player1"]
[Black "Player2"]
[Result "1-0"]

1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 e5 5. Nb5 a6 6. Nd6+ Bxd6 7. Qxd6 Qf6 8.
Qd1 Qg6 9. Nc3 Nge7 10. g3 d5 11. exd5 Nb4 12. Bd3 Bf5 13. d6 Bxd3 14. cxd3
Nxd3+ 15. Ke2 Nxc1+ 16. Rxc1 Nc6 17. d7+ Kd8 18. Re1 Nd4+ 19. Kf1 Qe6 20. Kg1
Nc6 21. Ne4 Qxd7 22. Qh5 Kc7 23. Qxe5+ Kb6 24. Qc5+ Kc7 25. Red1 Qe6 26. Ng5
Qf6 27. Ne4 Qe6 28. Nd6 Rad8 29. Qa5+ Kb8 30. Rxc6 Rxd6 31. Rcxd6 Qe7 32. Rd7
Qe4 33. Qc7+ Ka7 34. Qc5+ Kb8 35. Qd6+ Ka7 36. Qc5+ Kb8 37. Rd8+ Rxd8 38. Rxd8+
1-0

White played 36. Qc5. Fritz's Blundercheck came up with the following
"improvement":

{0.00  36.Rd4 Qe1+ 37.Kg2 Qa5 38.Rxb7+ Kxb7 39.Rb4+ Qxb4 40.Qxb4+ Ka8  6.78}

This means that Fritz saw 36. Qc5 as leading to an equal position, but scored
36. Rd4 as 6.78 in White's favour.

What is interesting about this is that the move played in the game, 36. Qc5,
actually forces mate in three! Something one would expect the best chess
programs to discover in a split second.

I decided to investigate this further with both the Friz 5.32 and the Fritz 6
engines, and neither one of the spotted that 36 Qc5 mates (ply 12).

On the other hand, when I pasted the EPD posion into Fritz it had no problem
finding the mate:

7r/kp1R1ppp/p2Q4/8/4q3/6P1/PP3P1P/3R2K1 w - -

(wKg1,Qd6,Rd1,d7,Pa2,b2,f2,g3,h2/bKa7,Qe4,Rh8,Pa6,b7,f7,g7,h7)

This looks like a bug in Fritz 6.

Cache was set at 64MB on a computer with 128MB (400 Mhz). Over 300MB available
on disk.

Dadi Jonsson



This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.