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Subject: Re: Reproducing a game (The ultimate dream of the debugger)

Author: Martin Giepmans

Date: 16:45:26 08/02/01

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If the OS behaves as it should there is no randomness caused by other programs,
interrupts or whatever.
And if your compiler behaves as it should the rnd-function will always generate
the same numbers (provided you use the same seed).
In fact these numbers are not random at all. The rnd-function only imitates
randomness.
Of course you can introduce "randomness" the hard(ware) way, by kicking your
computer, but there is really no soft way :)
Randomness is a always a sign of a hardware-problem.

Maybe I should explain what I have written earlier about node-counts.
Suppose your program produces a weird move. OK, you count the nodes, it
calculated 1888888 nodes, say. Now you set up the same position and you tell
your program that it should calculate the same number of nodes, no less, no
more, 1888888, period. (I this your idea? Or did I understand you wrong?)

Will your program play the same move? Will the score be the same?
Nobody knows, because different information in the hashtables (etc) gives a
different search-pattern (if this where not true then why would we use those
tables in the first place?)
Even the depth might not be the same:
The second time it starts from scrap, nothing in the hashtables, no killers,
etc, so it may need more then 1888888 nodes to complete depth 9, while the first
time (when it produced the weird move) it needed exactly 1888888 nodes to
complete depth 10.








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