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A trustless blockchain most certainly does. https://news.ycombinator.com/item?id=15915957 https://news.ycombinator.com/item?id=15915957

dozzie 9y ago
It most certainly doesn't. You even confuse blockchain and Merkle trees, and call into existence some weird term "distributed blockchain". But then, consensus problem is a problem of establishing a specific value for almost all participants. Which implies that the value is established, which means that the protocol terminates. Blockchain was not designed to ever terminate, so it's not a consensus protocol even if for no other reason. Otherwise, what parts of blockchain exactly establish a common value among participants and what exactly is this common value?
- zero-x 9y ago
  What? There is consensus on the public blockchain every few seconds + block depth. It's called Nakamoto consensus, so yes blockchain 'solves' the problem. In smaller chains, there can certainly be consensus, it just won't be as trusted as a public chain and 51% attacks are potentially more feasible due to it having a smaller economic barrier.
  - dozzie 9y ago
    > What? There is consensus on the public blockchain every few seconds + block depth. It's called Nakamoto consensus, so yes blockchain 'solves' the problem. It's a name used for Bitcoin's protocol. It doesn't mean it's consensus. How does the established value by this "consensus" protocol look like? And why do you consider it established, when other participants can have a totally different view of the list of documents in the protocol, or your view can change completely with next message? How is it an agreed value? And at what point should we look at the views of two different participants to see the same value? And how does it relate to Lamport's original publication about the consensus problem?
    - zero-x 9y ago
      The established value of the consensus is the transactions contained within the block. It's established because it's what the network accepted, regardless of individual node states. That's the point, one should not have to consider the values of other nodes to reach consensus. If the network agrees on something, that's consensus. If a certain node doesn't, that's their problem. It's agreed because that miner solved the block problem first. If you have a different view, you must fix it. This is how it achieves consensus. Not sure what specific consensus problem Nakamoto consensus doesn't solve, but it does provide a consensus based on the specific rules of the network. So yes, it's a consensus system. You might want to be contrarian and dispute what consensus means to you. But that's what it means to to the miners and that's what matters.
      - dozzie 9y ago
        > The established value of the consensus is the transactions contained within the block. Which of them? Because every node has a slightly different view and doesn't know how it differs from anybody else's view. > That's the point, one should not have to consider the values of other nodes to reach consensus. If the network agrees on something, that's consensus. If a certain node doesn't, that's their problem. The problem is that every node has slightly different view. You can't tell "this is the agreed value", because no particular node has this value as its state. Yet somehow it emerges as network's agreed value? By what means (algorithm) anybody can take a list of transactions and say "this is the network's agreed value"? Not to mention that the list of transactions constantly changes, you didn't address the problem that agreed value requires the protocol to terminate first. > It's agreed because that miner solved the block problem first. If you have a different view, you must fix it. This is how it achieves consensus. In what way is "solve block problem" consensus? > Not sure what specific consensus problem Nakamoto consensus doesn't solve, Yes, this is typical problem with blockchain enthusiasts. They're usually too uneducated and don't know the fundamentals, like the definition of consensus problem. I pointed you to Byzantine generals paper already, it should have been easy to find even with just "consensus problem Lamport" keywords.
        9y ago
- YuriNiyazov 9y ago
  You seem like you understand more than I do. ELI5 why agreeing on an ordering of timestamps on transactions is not consensus, but agreeing on a single value such as "attack" or "retreat" is consensus.

dozzie 9y ago

It most certainly doesn't. You even confuse blockchain and Merkle trees, and call into existence some weird term "distributed blockchain". But then, consensus problem is a problem of establishing a specific value for almost all participants. Which implies that the value is established, which means that the protocol terminates. Blockchain was not designed to ever terminate, so it's not a consensus protocol even if for no other reason. Otherwise, what parts of blockchain exactly establish a common value among participants and what exactly is this common value?

zero-x 9y ago
What? There is consensus on the public blockchain every few seconds + block depth. It's called Nakamoto consensus, so yes blockchain 'solves' the problem. In smaller chains, there can certainly be consensus, it just won't be as trusted as a public chain and 51% attacks are potentially more feasible due to it having a smaller economic barrier.
- dozzie 9y ago
  > What? There is consensus on the public blockchain every few seconds + block depth. It's called Nakamoto consensus, so yes blockchain 'solves' the problem. It's a name used for Bitcoin's protocol. It doesn't mean it's consensus. How does the established value by this "consensus" protocol look like? And why do you consider it established, when other participants can have a totally different view of the list of documents in the protocol, or your view can change completely with next message? How is it an agreed value? And at what point should we look at the views of two different participants to see the same value? And how does it relate to Lamport's original publication about the consensus problem?
  - zero-x 9y ago
    The established value of the consensus is the transactions contained within the block. It's established because it's what the network accepted, regardless of individual node states. That's the point, one should not have to consider the values of other nodes to reach consensus. If the network agrees on something, that's consensus. If a certain node doesn't, that's their problem. It's agreed because that miner solved the block problem first. If you have a different view, you must fix it. This is how it achieves consensus. Not sure what specific consensus problem Nakamoto consensus doesn't solve, but it does provide a consensus based on the specific rules of the network. So yes, it's a consensus system. You might want to be contrarian and dispute what consensus means to you. But that's what it means to to the miners and that's what matters.
    - dozzie 9y ago
      > The established value of the consensus is the transactions contained within the block. Which of them? Because every node has a slightly different view and doesn't know how it differs from anybody else's view. > That's the point, one should not have to consider the values of other nodes to reach consensus. If the network agrees on something, that's consensus. If a certain node doesn't, that's their problem. The problem is that every node has slightly different view. You can't tell "this is the agreed value", because no particular node has this value as its state. Yet somehow it emerges as network's agreed value? By what means (algorithm) anybody can take a list of transactions and say "this is the network's agreed value"? Not to mention that the list of transactions constantly changes, you didn't address the problem that agreed value requires the protocol to terminate first. > It's agreed because that miner solved the block problem first. If you have a different view, you must fix it. This is how it achieves consensus. In what way is "solve block problem" consensus? > Not sure what specific consensus problem Nakamoto consensus doesn't solve, Yes, this is typical problem with blockchain enthusiasts. They're usually too uneducated and don't know the fundamentals, like the definition of consensus problem. I pointed you to Byzantine generals paper already, it should have been easy to find even with just "consensus problem Lamport" keywords.
      - 9y ago
YuriNiyazov 9y ago
You seem like you understand more than I do. ELI5 why agreeing on an ordering of timestamps on transactions is not consensus, but agreeing on a single value such as "attack" or "retreat" is consensus.