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From: John Tromp <john.tromp@gmail.com>
Date: Fri, 25 Sep 2020 19:23:46 +0200
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To: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
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Subject: Re: [bitcoin-dev] Floating-Point Nakamoto Consensus (bitcoin ml)
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Re: Floating-Point Nakamoto Consensus (bitcoin ml)
>

> This is a pretty big departure from cumulative POW.

It's still cumulative. But instead of cumulating network difficulty,
they cumulate log_2(solution difficulty).

So if two solutions are found simultaneously, and one has a hash
that's only half of the other, then that will have twice the solution
difficulty and thus contribute 1 more the cumulate log_2(solution
difficulty).

> Could you explain to me what you see happening if a node with this patch
> and no history starts to sync, and some random node gives it a block
> with a better fitness test for say height 250,000? No other solution
> will have a better fitness test at that height, so from my understanding
> its going to stop syncing. How about even later - say this proposal is
> activated at block 750,000. At 850,000, someone decides it'd be fun to
> publish a new block 800,000 with a better fitness test. What happens the
> 50,000 blocks?

Nothing happens in these cases, as the new blocks are still far behind
the tip in cumulative score (they just have higher score at their
height).

regards,
-John