On 5 November 2013 22:07, Quinn Harris <btcdev@quinnharris.me> wrote:

I don't think choosing the block with the lowest hash is the best
option. The good and bad miners have an equal probability of finding a
lower hash. But after Alice finds a block she can easily determine the
probability that someone else will find a lower hash value that meets
the difficulty requirement. This can be used to judge if its best to
start working on the next block or work on finding a lower value hash to
increase the chance her block is used.

Well in that case, you could make it unpredictable by choosing based on a hash of the blockhash and chose the lowest from two. There is no way for Alice to know if Bob's resulting hash will be higher or lower than hers since she does not know Bob's blockhash in advance and therefore she would be better broadcasting her block immediately.

You could even add another unpredictable factor: deciding the rules of whether higher or lower wins by hashing both competing blockhashes. If the leading two hex digits are below 128 lower wins, and if above, higher wins.

Drak