shafemtol on Nostr: These are the concerns and edge cases I can think of regarding a soft fork to set a ...
These are the concerns and edge cases I can think of regarding a soft fork to set a maximum timestamp limit on block 2015:
## Can a maximum timestamp requirement of prev timestamp + 20 min conflict with the minimum timestamp requirement of prev mediantime + 1 sec, making it impossible to mine a new block on top of the latest one?
No, because prev mediantime can not be greater than prev timestamp. The mediantime of a block is the median of the timestamps of that block and the 10 before it. Because that block itself must have a timestamp greater than the median of the 11 blocks before it, it must have a timestamp greater than that of at least 6 of those blocks. It follows that it must have a timestamp greater than at least 5 of the 10 blocks before it. Thus, its timestamp can only be set so low as to also define the block's own mediantime.
## Could non-upgraded miners run off in a chain split?
Yes, if they start a block storm. But they would reorg and join the upgraded chain as soon as the upgraded chain finds block 2015. This is because the non-upgraded chain would all consist of difficulty-1 blocks for the next 2017 blocks (and then increasing by no more than 4x for every difficulty period after that). That is, the blocks do not make a heavy chain. Even if the non-upgraded chain had more hashing power in theory, they would be limited by the rate of new blocks having to be sent across the network.
## Could the chain stop at block 2014 for hours because all ASIC miners left?
This is a possibility. Is it worse than a block storm, though? Not everyone has their own ASIC miner, but renting some ASIC time shouldn't be too hard or expensive (should cost no more than about 40 cents per expected block at the current difficulty and BTC price).
## Can a maximum timestamp requirement of prev timestamp + 20 min conflict with the minimum timestamp requirement of prev mediantime + 1 sec, making it impossible to mine a new block on top of the latest one?
No, because prev mediantime can not be greater than prev timestamp. The mediantime of a block is the median of the timestamps of that block and the 10 before it. Because that block itself must have a timestamp greater than the median of the 11 blocks before it, it must have a timestamp greater than that of at least 6 of those blocks. It follows that it must have a timestamp greater than at least 5 of the 10 blocks before it. Thus, its timestamp can only be set so low as to also define the block's own mediantime.
## Could non-upgraded miners run off in a chain split?
Yes, if they start a block storm. But they would reorg and join the upgraded chain as soon as the upgraded chain finds block 2015. This is because the non-upgraded chain would all consist of difficulty-1 blocks for the next 2017 blocks (and then increasing by no more than 4x for every difficulty period after that). That is, the blocks do not make a heavy chain. Even if the non-upgraded chain had more hashing power in theory, they would be limited by the rate of new blocks having to be sent across the network.
## Could the chain stop at block 2014 for hours because all ASIC miners left?
This is a possibility. Is it worse than a block storm, though? Not everyone has their own ASIC miner, but renting some ASIC time shouldn't be too hard or expensive (should cost no more than about 40 cents per expected block at the current difficulty and BTC price).