With 8 hashes per position, the chance of two different boards producing a different set of hashes but the same canonical hash is greater than 1/2^64, because there will be a bias in the choice of canonical
hashes - toward numerically lower numbers, for instance.

I think.

Arthur




On Dec 20, 2007, at 10:49 AM, Jacques Basaldúa wrote:
<snip>
The idea is that any of the board the can be transformed by mirror rot from a given board will produce the same set 8 hashes, just in a different order. Because the hashes are (with high probability) unique, one hash represents a board and the canonical hash represents the class of 8 boards produced by mirror/rot.

It is true: Another board in the class -> same set of 8 hashes -> same canonical hash. It is almost certain (prob = 1/2^64 per check): A different board - > a different set
of 8 hashes -> different canonical hash.

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