[bitcoin-dev] [Bitcoin Advent Calendar] Decentralized Coordination Free Mining Pools

[Billy Tetrud]

Looks like an interesting proposal, but it doesn't seem to quite match the
goals you mentioned. As you do mention, this mining pool coordination
doesn't get rid of the need for mining pools in the first place. So it
doesn't satisfy item 1 on your goal list afaict.

The primary benefits over what we have today that I can see are:
1. increased payout regularity, which lowers the viable size of mining
pools, and
2. Lower on chain footprint through combining pay outs from multiple pools.

Am I missing some?

These are interesting benefits, but it would be nice if your post was
clearer on that, since the goals list is not the same as the list of
potential benefits of this kind of design.

As far as enabling solo mining, what if this concept were used off chain?
Have a public network of solo miners who publish "weak blocks" to that
network, and the next 100 (or 1000 etc) nice miners pay you out as long as
you're also being nice by following the protocol? All the nice
optimizations you mentioned about eg combined taproot payouts would apply i
think. The only goals this wouldn't satisfy are 3 and 5 since an extra
network is needed, but to be fair, your proposal requires pools which all
need their own extra network anyways.

The missing piece here would be an ordering of weak blocks to make the
window possible. Or at least a way to determine what blocks should
definitely be part of a particular block's pay out. I could see this being
done by a separate ephemeral blockchain (which starts fresh after each
Bitcoin block) that keeps track of which weak blocks have been submitted,
potentially using the pow already in each block to secure it. Granted that
piece is a bit half baked, but it seems quite solvable. Wdyt?

One thing that jumped out at me as not safe is throwing block rewards into
a channel and being able to spend them immediately. There's a reason block
rewards aren't spendable for a while, and channels don't solve that
problem, do they? Why not simply reduce the on chain wait time for spending
block rewards at that point? Seems like the consequences would be the same.

On Tue, Dec 14, 2021, 16:12 Bob McElrath via bitcoin-dev <
bitcoin-dev at lists.linuxfoundation.org> wrote:

> You are hand waving. Attempting to redefine terms to justify your argument
> is
> intellectually dishonest. Bitcoin pools have *always* been about variance
> reduction. Your window function fundamentally CANNOT be used to hedge
> hashrate.
> Various suggestions below introduce dangerous new games that might be
> played by
> miners.
>
> The fact is that the half-baked design you posted is less than useless, and
> doesn't do anything that anyone wants.
>
> You are trying to justify CTV by making it be all things to all people.
> "When
> all you have is a hammer, every problem looks like a nail".  Instead I
> humbly
> suggest that you pick ONE problem for which CTV is demonstrably the right
> and
> best solution, instead of snowing us with a ton of half-baked things that
> *could* be done, and often don't even require CTV, and some (like this one)
> fundamentally don't work. I do like some of your ideas, but if you had to
> pick
> just one "use case", which would it be?
>
> Jeremy [jlrubin at mit.edu] wrote:
> > Bitcoin didn't invent the concept of pooling:
> https://en.wikipedia.org/wiki/
> > Pooling_(resource_management). This is a Bitcoin Mining Pool, although
> it may
> > not be your favorite kind, which is fixated on specific properties of
> computing
> > contributions before finding a block. Pooling is just a general
> technique for
> > aggregating resources to accomplish something. If you have another name
> like
> > pooling that is in common use for this type of activity I would be more
> than
> > happy to adopt it.
> >
> > This sort of pool can hedge not only against fee rates but also against
> > increases in hashrate since your historical rate 'carries' into the
> future as a
> > function of the window. Further, windows and reward functions can be
> defined in
> > a myriad of ways that could, e.g., pay less to blocks found in more rapid
> > succession, contributing to the smoothing functionality.
> >
> > With respect to sub-block pooling, as described in the article, this
> sort of
> > design also helps with micro-pools being able to split resources
> > non-custodially in every block as a part of the higher order DCFMP. The
> point
> > is not, as noted, to enable solo mining an S9, but to decrease the size
> of the
> > minimum viable pool. It's also possible to add, without much validation
> or
> > data, some 'uncle block' type mechanism in an incentive compatible way
> (e.g.,
> > add 10 pow-heavy headers on the last block for cost 48 bytes header + 32
> bytes
> > payout key) such that there's an incentive to include the heaviest ones
> you've
> > seen, not just your own, that are worth further study and consideration
> > (particularly because it's non-consensus, only for opt-in participation
> in the
> > pool).
> >
> > With respect to space usage, it seems you wholly reject the viability of
> a
> > payment pool mechanism to cut-through chain space. Is this a critique
> that
> > holds for all Payment Pools, or just in the context of mining? Is there a
> > particular reason why you think it infeasible that "strongly online"
> > counterparties would be able to coordinate more efficiently? Is it
> preferable
> > for miners, the nexus of decentralization for Bitcoin, to prefer to use
> > custodial services for pooling (which may require KYC/AM) over bearing a
> cost
> > of some extra potential chainload?
> >
> > Lastly, with respect to complexity, the proposal is actually incredibly
> simple
> > when you take it in a broader context. Non Interactive Channels and
> Payment
> > Pools are useful by themselves, so are the operations to merge them and
> swap
> > balance across them. Therefore most of the complexity in this proposal is
> > relying on tools we'll likely see in everyday use in any case, DCFMP or
> no.
> >
> > Jeremy
> > !DSPAM:61b8f2f5321461582627336!
> --
> Cheers, Bob McElrath
>
> "For every complex problem, there is a solution that is simple, neat, and
> wrong."
>     -- H. L. Mencken
>
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