[bitcoin-dev] difficulty adjustment (was: The Nuclear Option: BIP148 + MR POWA)

[Henning Kopp]

Hi,

> I would also highly advise finding a simple and robust difficulty adjustment
> that occurs every block instead of bitcoin/litecoin's 2016 block use.

I also thought about this some time ago. But note that this implies
that forks grow with the same block frequency as the main chain. Thus
the longest chain rule becomes irrelevant, since all chains will have
the same length (in expectancy). Rather, the chain with most work is
the true one.

Best
Henning


On Wed, Jul 05, 2017 at 02:02:08PM +0000, Troy Benjegerdes via bitcoin-dev wrote:
> The fastest way to triple Bitcoin capacity is to split the network into
> two or three different blockchains. We encourage forks of software, why
> are blockchains somehow different?
> 
> Yes, this is risky, and probably volatile.
> 
> I honestly don't expect lots of people with large amounts of money 
> invested (exchanges, financial institutions, etc) to go along with 
> something like this, and that say 90% of the wealth with stay concentrated
> in whatever chain has the majority SHA256 hashpower.
> 
> But as a game-theory excercise to see who's theories actually work?
> 
> I highly encourage a real-world test of all these theories.
> 
> I would also highly advise finding a simple and robust difficulty adjustment
> that occurs every block instead of bitcoin/litecoin's 2016 block use.
> 
> On Wed, Jul 05, 2017 at 09:18:36AM +0000, John Hardy via bitcoin-dev wrote:
> > This idea is highly contentious as it would guarantee a viable chain of Bitcoin with SegWit activated whether BIP148 gained sufficient support or not. I am not necessarily advocating it - just putting it out for discussion. While the downside is that it could permanently split the network, the upside is that it could heap additional pressure on miners to follow the BIP148 chain and ensure a minimally disruptive upgrade. This is pure game theory.
> > 
> > 
> > 
> > MR POWA (Mining Reactive Proof of Work Addition) is a method to introduce an additional proof of work to a blockchain in response to a detected mining behaviour.
> > 
> > 
> > 
> > In the case of BIP148, the criteria for activation could be when the software detects a non-BIP148 compliant chain that is 144 blocks (24 hours) ahead of a BIP148 compliant chain.
> > 
> > 
> > 
> > At this stage the software would change its consensus rules (hard fork) to do two things:
> > 
> >   *   Lower the difficulty for existing PoW method (SHA256).
> > 
> >   *   Introduce a second POW method, such as Scrypt or Ethash, that is incompatible with SHA256 hardware but already has an established mining industry for altcoins.
> > 
> > 
> > 
> > The difficulty should be low, and blocks will initially be found much more quickly than every 10 minutes until the difficulty adjusts. Each method would have its own difficulty. It could be a requirement that POW methods alternate to neutralise attacks from the other chain.
> > 
> > 
> > 
> > This would guarantee SegWit activation. Anybody who is already running a BIP148 node could just as easily run a BIP148 + MR POWA node. This could not realistically be supported by Core and would have to be implemented in a grassroots movement, similar to BIP148.
> > 
> > 
> > 
> > Ideally, it would just force the miners to follow the BIP148 chain (or risk the value of their hardware being hurt) and the code would never be activated. MR POWA would mean BIP148 miners would no longer need to ?hold their nerve? as they would be guaranteed a viable chain and rewarded for their early support.
> > 
> > 
> > Regards,
> > 
> > 
> > John Hardy
> > 
> > john at seebitcoin.com
> > 
> > 
> 
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> 
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-- 
Henning Kopp
Institute of Distributed Systems
Ulm University, Germany

Office: O27 - 3402
Phone: +49 731 50-24138
Web: http://www.uni-ulm.de/in/vs/~kopp