Fritz 11 doesn't agree with my engine

[cms271828]

Hi

I have a position

8/2B5/8/3kN3/2pN4/2K3P1/8/8 w - - 0 1

My engine solves it in 11 ply:
Nxc4 Kc5, Ne5 Kd5, Nd3 Ke4, Kc4 Ke3, Bf4+ Ke4, Nc5#

I got this puzzle from a book, which gives Bb8 as key.

I've gone through all the variations, so I know my solution is also correct.


After running same position on Fritz 11, it finds the sequence:
Bb8 Ke4, Ng4 Kd5, Nf6+ Kc5, Nd7+ Kd5, Bf4 Ke4, Nf6#

And this is the fine, my problem is that it also displays the line:
Nc4 Ke4, g4 Kd5, g5 Ke4, g6 Kd5, g7 Ke4, g8=Q (not mate)

I don't get why it doesn't show the mate starting with Nc4.

Is that normal? Thanks

[adieguez]

Is that normal? Thanks

Not much. You welcome.

[cms271828]

Not a particularly helpful response, why bother?

[adieguez]

hi am sorry, maybe even on this position Fritz does some null-move, what else could it be I don't know. A bug?

Its losing anyway, who knows, maybe in that case it does some crazy stuff to surprise the oponent's mind/logic.. another possibility.

Maybe its on purpose to make people post about it.

There are even more possibilities but first am sorry again if this another post is not of your taste.

Not a particularly helpful response, why bother?

[Dann Corbit]

[d]8/2B5/8/3kN3/2pN4/2K3P1/8/8 w - - acn 357307; acs 0; bm Bb8 Ng6 Nxc4; ce 32756; dm 6; pv Nxc4 Kc5 Nb2 Kd5 Nd3 Ke4 Kc4 Ke3 Bf4+ Ke4 Nf2#;

There are three moves:
Bb8, Ng6, Nxc4 that are all equally good and a checkmate in 6 moves.

That's why this is a poor test position.

[metax]

Interesting thing... In my engine, when I _disable_ transposition tables, the mate in 5 after Nxc4 is seen after 9 secs on ply 11. When I enable hash tables, it doesn't see the mate until ply 15 and 19 secs.
I don't think it's a null move problem because ChessMind and I think most other engines turn off null moves if one side has no more material left.

edit: Fritz 7 on my computer wants to play 1.g4, Shredder 11 likes 1.Ng4 and Rybka plays the mate in 6 after 1.Nxc4 after 1 sec on ply 8.

[Dann Corbit]

Interesting thing... In my engine, when I _disable_ transposition tables, the mate in 5 after Nxc4 is seen after 9 secs on ply 11. When I enable hash tables, it doesn't see the mate until ply 15 and 19 secs.
I don't think it's a null move problem because ChessMind and I think most other engines turn off null moves if one side has no more material left.

edit: Fritz 7 on my computer wants to play 1.g4, Shredder 11 likes 1.Ng4 and Rybka plays the mate in 6 after 1.Nxc4 after 1 sec on ply 8.

This is something worth investigating. If it were me, I would try very hard to get to the bottom of it.

[metax]

What I wrote is not reproducible, so forget it.