Topic: IOTA - page 743. (Read 1473405 times)

"Home-made" and "profanation" wasn't intended to insult you, sorry if it looks so, English is not my native language and sometimes I have to look words in an online translator that returns several results.

On the matter, if you don't agree then we can't continue the discussion because we stick to different paradigms. I prefer one which is used in the most papers dedicated to CAP theorem.

One more time I will help you, although the wisest action from a competitive standpoint would have been for me to not respond and let you continue with your perspective.


Obviously yes, if we agree that consistency of disallowing double-spends into the ledger and not reversing the time ordering of transactions is our desired consistency.


That is quite an absurd proposition you have made to say that eliminating the prevention of double-spends and allowing reversal of time ordering of transactions amongst differing graphs seen globally as being some useful form of consistency. There are no decisions that can be made from such mayhem. No one can decide who owns what. That is consistency   


Obviously I don't agree with such absurd nonsense. Sorry but I find the hubris in the way you phrased your nonsense ("home-made", "profanation") to deserve an equal reaction.

Let's start from this point.

I find your definition of "consistency" unsuitable for cryptocurrency analysis. I could create millions different instances of a ledger in such a way that they can be merged into a single instance without a single double-spending at all. Do we see consistency in such the case (before merging)? Obviously, not. Note that CAP theorem is used on a more abstract level than the level of account balances. I can imagine a perfectly consistent distributed system (by sacrificing A and P) which sees all double-spends that have ever happened. If we use your definition of "consistency" then we'll get an absurd result. I suggest to stay away of home-made definitions because they will lead to profanation of Brewer's theorem and won't let us to do a proper analysis.

Once you agree with me on the above we'll move to the next point.

Consistency in our case is the probability of a double-spend (and the inability to reverse a record of a completed transaction, which is involved in the same probability), since that is the only consistency that we need. Consistency of topology seems to be irrelevant as a direct metric of any consistency that concerns the goal of the consensus.

Your white paper provides an equation for that probability with examples on page 14.

But afaik, you have not yet characterized how A or P declines as the probability of a double-spend declines. Additionally it is not clear if the equation is proven and one potential path towards validating it is to be able to relate analytically how A and P are affected as that probability changes.


The probability of a double-spend is given by the probability of a chain being orphaned.

It seems the difference in our thinking is you have not yet formulated a metric of consistency relevant to our application of network consensus (a.k.a. Byzantine fault tolerance and coherence). It is all about the double-spending prevention, and not the bass.


Ah I am a conceptual (abstract) thinker. You are thinking as a low-level network engineer, thus you miss the generative essence of how CAP applies. The availability of the P2P network is really irrelevant conceptually to how CAP relates to the goal of the consensus network— to order transactions in time and prevent (or record and blacklist) double-spends. Thus availability in the relevant conceptual context is the ability to extend the chain AUTONOMOUSLY. If for example in any alternative design the chain could only be extended after tallying a quorum, then availability would require a quorum to be present. The reason that proof-of-work is such an elegant solution to the Byzantine Generals issue, is because the solution is generated by autonomous actors (and thus the entropy of the system is open and not closed).

Until you understand conceptually, you can't begin to understand block chain scaling holistically.

And now I am giving away too much of my expertise for free to a potential competitor to my work. So I will need to stop. I had suggested we work together, because I had been thinking about these issues for a long time and I thought your DAG might offer some unique aspects towards formulating a holistic design for various CAP tradeoff scenarios. But now I need to see more analytical justification of your design before applying any more of my effort. The ball is now in your court. Knowing how people react to my statements, apologies in advance if this seems egotistical to any one, then they need to read this (meaning it would their ego and not mine, I am just stating objectively what I think...no ego involved).


Agreed.


I already showed mathematically how to defeat the selfish mining attack.


My stance (unless something shatters my perspective) is that it is now up to you all to formulate more compelling holistic explanation/characterization of your DAG within the context of the CAP theorem, and also provide analytical models.

I don't think I am being paid nor am I a team member, so therefor I shouldn't be trying to dig into the details of that. I have provided what I believe to be the relevant conceptual framework (you may disagree). And I have work to do on my own block chain scaling technology.

Good luck. I'll check back sometimes on progress.

I don't agree with the red part, it's impossible to have an equation for probability (has anyone ever had it?) because it depends on network topology which is infeasible to measure (it even changes every minute).



Bitcoin has eventual consistency, probability of an orphaned chain has nothing to do with it unless you consider the case of spherical Bitcoin in vacuum.



Availability in Bitcoin is nine nines, ability to extend the longest chain is irrelevant there.



Partition tolerance in Bitcoin is pretty high, this is achieved with the help of coinbase maturity parameter, if it was set to zero we would see more transactions not reincluded into the longest chain after a reorg.



51% attack is an attack for another case of spherical Bitcoin in vacuum. Ittay Eyal and Emin Gun Sirer showed that Bitcoin can be successfully attacked even with 33%/25% of hashing power.


PS: Looks like we are NOT on the same page. I suggest to spend one day to come to a common denominator of our points of view and after that continue discussion about tangle and CAP.

If Consistency is weakened to eventual, then either you have no defined Consistency (i.e. no Consistency ever) or you have an equation for probability of Consistency. If there exists such an equation, then you have to explain how and the probability of either Availability or Partition tolerance is lost when the probability of Consistency is attained. The onus is on your to justify these claims analytically, including convincing arguments about the game theory. Else you can just put it into the wild and observe (and who knows what will happen).


Consistency in Bitcoin is the fact that the objectivity is the longest chain. There only state of inconsistency is the probability of an orphaned chain, which declines over time except if the adversary has greater than 50% of the sustained network proof-of-work hashrate.

Availability in Bitcoin is given by even if there are no other active nodes, then sender and/or recipient of the transaction can extend the longest chain and the Consistency remains valid (except for the caveats on Consistency).

Partition tolerance is lost in Bitcoin because if there is network partitioning then double-spends can occur on each chain without being detected until these chains are merged. Bitcoin can't tolerate multiple chains, and only allows the longest chain.  There is no way to merge these chains, because double-spends can infect other downstream transactions, combined with inputs from legitimate transaction graphs.

So what we can say is Bitcoin fulfills the CAP theorem, except it has theoretically unnecessary caveats in Consistency due to 51% attack and delay due to probability of orphaned chains, which are due to the ephemeral Partition tolerance that is introduced by chain reorganization. The Consistency delay also causes transaction confirmation to be significantly delayed. The goals of my Sync (or BlocSync) block chain overhauled design has been to eliminate those caveats, while relaxing the Consistency and/or Availability during partitioning of the network in order to provide some Partition tolerance.


If the CAP theorem is random to Byzantine fault tolerance for networks, then we might as well say the speed-of-light is an irrelevant fact when doing Physics.

Everyone will know in due time, don't worry:)

Consistency is weakened to eventual.

To make sure we are on the same page: what is partition tolerance and availability of Bitcoin?

Okay what did you give up: C, A, or P? Remember you said I am wrong, so surely you can answer this very quickly right 

CfB and mthcl, the onus is on you to prove and demonstrate what you have given up from the CAP theorem. You have not. Period.

Nice article! Good use cases mentioned in the articles. Another use case can be the medical data collection. Like Iwatch and Fitbit can collect medical data from individuals to resell to doctors/health organizations and pharmaceutic companies by micro-paying the individuals for the data.

If, for example, I'm a merchant who accepted a payment in the "smaller" branch, then I have all the motivation to do some more PoW to make the branches re-merge and therefore increase my safety.  And please stop randomly citing Big Important Theorems that have only a vague connection to what we are discussing. In academic circles such behaviour is not welcome.

Sorry, but you are wrong. It's silly to build a distributed system violating CAP theorem, in no circumstances anyone of us would even attempt that, it's the same as trying to fly faster than speed of light.

Due the quoted Prisoner's Dilemma that I outlined (for which I believe your response was inadequate for the following reason) in that no one has an incentive to be first to lengthen the tips, the game theory is going to devolve to everyone agreeing to blacklist double-spends without actually abandoning branches containing conflicting transactions where they have transactions.The Prisoner's Dilemma is only solved in favor of lengthening if double-spends won't cause a branch to be illegitimate. Thus the branches will diverge while they lengthen. Your preferred algorithm will not hold over time. CAP's theorem is guidance, and now you just need to model it or put it into the wild and observe.

You might try to formulating some fencing or "longest-path" algorithm, but you are just going to end up back at a block chain (giving up Partition tolerance) once you have solved the Consistency and Access issues.

Any way if I am wrong, then kindly be the first to disprove the CAP theorem. Good luck with that.

I have seen a statement up thread by one of you three about branches being able to remerge.

I think it is pretty clear from the white paper and general discussions that there was assumed to be some magic here without explaining that you must give up something when restoring the partition intolerance of a block chain.

So I just want you all to enumerate what you are giving up specifically. Seems like you are still working this out, so I am just giving you some food for your thought process.

Peer review. And I think readers need to read review and see your responses.

Why? If there are no conflicting tx's, someone can issue a tx referencing 1 tx from partition 1 and 1 tx from partition 2, et voila.

Okay good, you are doing what I had explained to do. Who was first to document this strategy in public myself or you or some other?

But unless you actually enforce the vestment amounts to a small amount per individual, then you might have a difficult time arguing in court that you were not marketing to investors, given where you've announced this coin and especially if you are allowing an individual pay $5000 for your software.

Where was that promise given?

For example to deal with the double-spend attack stdset has been discussing, to maintain consistency and access you must do something to "fence off" partitions (branches) and give up P.

The block chain creates one partition which is the longest chain. Thus it can maintain C and A. You will have to give up one of C, A, or P. The promise of DAG was to not give up any of those.

I think you can make DAG work but you will end up with divergent partions that can't be remerged (thus losing global consistency of value), same as what will happens to Bitcoin if it is forked (even by network partitioning).

This is a serious fundamental theorem that all of us designing consensus algorithms face.

We're not marketing to investors. We're going to have a software sale. The tokens are software. Like I said: we make no promises to any investors of these software tokens increasing in value.

All of this will be made even more clear in the ICO announcement of course.

If they did not register with the SEC, then I think their models are illegal, unregistered securities, but IANAL, so consult your own. You can read my complete analysis at the thread I linked to. The key point is marketing to investors.