Author: Will Singleton
Date: 13:30:01 02/18/99
Here are the results:
<=5 6 7 8 >=9
Fritz 5.32 dxe5 dxe5 dxe5 dxe5 dxe5
Hiarcs 6 Nh4 Nh4 Be3 Be3 Be3
MacChess 4 dxe5 dxe5 dxe5 dxe5 Bc1
Crafty 16.5 dxe5 Bc1 Bc1 Bc1 Bc1
Amateur 0.91 dxe5 dxe5 dxe5 dxe5 Bc1
PostModernist 0.9 Nh4 dxe5 dxe5 Bc1 Bc1
EXchess 2.5x Bc1 Bd2 Bc1 Be3 Be3
LambChop 7.x Bc1 dxe5 Bc1 Bc1 Bc1
Gromit 1.2? --- --- --- dxe5 Nh4
Robertson 0.0 Bc1 Bc1 dxe5 dxe5 dxe5
Ferret Bc1 or dxe5, whatever
InmiChess --- --- Nh4 Nh4 Nh4
Diep classified (private email :), but it wasn't dxe5)
Thanks for all your responses, we have some interesting results.
A couple of issues here -- the first is that the position
occurred in a blitz game, so only about 10 seconds was available
to move. As it turns out, the position is already bad, -1 or
so (as Bruce says, White is hosed), so there's no real good move
-- but short term, there is a wide variety of opinion between
the various programs. This has significance for blitz play,
especially considering that dxe5 is probably the best move!
I thought it might be interesting to analyze the reasons for the
diversity of move selection. Some programs see deeper for a
given ply depth, of course. Do they pay a price for this by
having to take longer to iterate to a given ply? Or does the
deeper search (more extensions) result in better ordering, which
causes the desired ply to be reached even sooner?
The position is fairly complex, and I would expect lots of
extension triggers. For example, Hiarcs is known (I think) to
extend quite a bit. I ran this with Hiarcs 6, and it never
considers dxe5 (as the best move) through many minutes of
searching. But after dxe5 a4 Qxa4 fxe5 Qxc4 etc, it has a
better eval for white than it did with any alternative to dxe5
originally. So it looks like it missed what it later considers
to be the best move, which is dxe5!
Bc1 is worse (or no better) because of a4 Qb4 Re6 Nh4 Rb6 ...
Be3 is worse (or no better) because of exd4 cxd4 Re6 Re3 Rb6 ...
Maybe Bob has a bug. :) In both outputs I received, Crafty
doesn't see the proper continuation after dxe5. And I believe
Dann said that it may have switched back after a long think.
Interestingly, Jim Walker says that Fritz 5.32 prefers dxe5
throughout a long search. I would like to see the pv output on
that. Why does Fritz remain constant on what is probably the
best move, while others are all over the lot?
Will
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