"JohnnyT" wrote in message
. ..
David Richerby wrote:

Do you have any guess (or, shock!, data) on how often errors occur in
WC games that an engine (given reasonable time) would score down by
say 100cp?

I will say, that in my own practical experience, running through games. That
in the same, and not unusual positions, that Fritz 8,9,and 10 have evaluated
positions over 100cp different than Rybka 2.3.1 And that different moves
have been suggested.

That alone should provide enough of a question as to the results here. The
fact is that we don't know when the engines will be strong enough to represent
the "truth".

In theory, the engine being too strong could be a source of error
in the analysis, as much as the engines being too weak could.

For example, the best move leads to a win in 20 moves based on
a complicated calculation that no human considers. The second
best move wins more slowly but in a way that strong GMs might be
able to see.

Player makes the best move (for the wrong reasons) overlooking the
alternate way to win. That's evidence of weaker, not
stronger, play.

This happens all of the time if you look at scholastic games. Crafty
sees the win of a rook at 8-ply and deems it superior to winning
a piece at 3-ply. But the 8-ply analysis is essentially irrelevant to the
game because the kids are not able to calculate that deeply.



I will say that I do not use Crafty for day-to-day analysis so I don't have an
opinion other than that you need to remember in ELO that the difference
between 2500 and 2800 is vast, and the difference between 2800 and ~ 3100 is
as vast. It is not 10% better, it is closer to think of it as TWICE as good.
Or more likely to win MOST of the time. It is a HUGE difference.