"henri Arsenault" wrote

There does seem to be an occasional evaluation bug in Fritz8- at least
in the infinite analysis mode.

A number of times, Fritz has given an obviously bad move a (= 0.00)
rating, independently of how long I wait. But if I play the move, it
immediately shows it to be worth as low as -6. This is always
characterized by the display not showing any moves for this particular
move - just the first move. Clearly it is not kept as part of the
analysis. This has always happens as much as I can remember when the
position being analyzed was losing.

Unfortunately I did not save the positions, but it has happened more
than once or twice. It is not so serious in analysis, since it is so
obvious, but if Fritz does this while playing, then it could affect its
performance (unless it only happens when already losing).

This might be a situation where a computer uses kind of lazy repetition
detection. Many programs do this. Basically they don't check for 3-fold
repetition. Instead, they only check for 2-fold repetition, and if a
position occurs twice, the computer assumes that it will occur a third time.
The computer works in a way such that it assumes both players are playing
perfectly (it's not really true, but that is how the computer "thinks" about
its move). To learn more about why this might have occured, read Bruce
Moreland's webpage:
http://www.brucemo.com/compchess/pro...repetition.htm