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I've seen two different BIP103's and choose to not write about it because risk of ambiguity. One of them are proposing a linear growth and the other one is proposing an exponential growth. The all-linear growth is an option that will not work well in the future because the growth will be too slow soon or later. The exponential growth assumes that the technology will rise in a certain growth, which may be too slow or too fast in accordance to the technical evolution. None of the BIP103 proposals will actually handle an unexpected future case.

BIP105 has another feature not mentioned in my proposal that is to place a vote requires a cost as a difficulty increase. I do not think it's a good option since it will make users refrain from voting to "earn" a difficulty lowering. The votes are the (yet) only soft way I see to let the blockchain know if it should allow growing faster or slower. I also don't see a benefit of having the opportunity to lower the block max size in comparison to the risks involved with that. Then it proposes a limit to how much it can increase at all which will need a new hard fork when we need to increase the limits of the proposal.

I don't see how John Sacco's BIP proposal is similar to this one since there is no voting mechanism to make the increase dynamic. Also John proposes that the size will double at each halving instead of each difficulty retarget. This could, in contrary to increase the fees by making larger spaces in the blocks, decrease the fees because of that the fee required to enter the next block will be lowered. Also it proposes a hard limit at 32 MB which, again, need a new hard fork later.

The formula I've provided isn't actually complicated. The 2^(1/2...) formula creates a number in the interval 1 to 2. The formula can tell if the block max size every second year shall double or be the same based on the last 6 month of votes. Because i believe there should always be an increase to secure a stable growth of the network, there is also a linear formula that the growth cannot be lower than. If the 2^(1/2...) formula gives a lower increase than the linear value for the next retarget, then the linear value should be used instead.

There will not be a rounding error since the implementation shall floor the value to a whole byte. The next size should be calculated on that value. Also, if the block max size is included in the retarget block, there would be an extra correcting method to uncertain clients. The formula isn't very different in complexity from the difficulty retarget formula and will still need the last recalculated value to be computed.

One of the benefits of using an exponential formula is that it could easily be fit for any arbitrary block period by changing the divisor. I personally think the two week interval will be smooth enough.

Erik

Den 2015-11-13 kl. 20:37, skrev Luke Dashjr:
> On Friday, November 13, 2015 1:07:33 PM Erik via bitcoin-dev wrote:
>> Hi devs. I was discussing the BIP proposals concerning max block size
>> yesterday in the #bitcoin channel. I believe that BIP101 fully utilized
>> will outperform consumer hardware soon or later and thereby centralize
>> Bitcoin. I would therefore like to do a different proposal:
>
> It doesn't look like you've considered BIP103 or newer BIPs? Especially, I'd
> suggest you look at and work with John Sacco who just the other day posted a
> BIP draft very similar-looking to yours. My overall impression of your summary
> is that it is unnecessarily over-complicated and underspecified. How does the
> 2^(1/2) block size limit actually work? This is not a very precise number, so
> it seems liable to produce rounding errors in different implementations.
> Additionally, the miner voting thing seems pointless since miners can already
> softfork lower limits. It would be beneficial to express the current
> possibility so full nodes can enforce it, but this would be expressed as an
> unlimited simple-majority vote to reduce the limit. Probably it would be ideal
> to separate this off from the hardfork BIP, since it's fairly tangent to it.
>
> Luke

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