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How is the 'Relativity of simultaneity' in observing the best confirmed double-spend in a COO-less Tangle resolved?

For example, in answering this question, it was answered that the double-spend "which is directly and indirectly referenced by more transactions (i.e. has a larger cumulative weight) will most probably get confirmed."

However, the problem remains that in a COO-less Tangle, the position of the observer also plays a role in determining which spend has a larger cumulative weight.

In one node the transaction T1 might be decided to take precedence. In another node, at the same time, T2 might be decided to take precedence. On top of that, a few moments later, each node might still come to a different conclusion.

So for the understanding of participants, where a dispute could occur as to what the state of the network is, how is the problem introduced by 'Relativity of simultaneity' solved?

  • Basically, you are asking how a double spend is resolved ? no ? – ben75 Dec 20 '18 at 22:13
  • I am asking how a double spend is resolved when the nodes used by each party report a different answer due to their network location. I.E. Two parties following the same rules, in the same network, can still have two different consensus outcomes depending on where and when their tests occur. – The Coordinator Dec 20 '18 at 23:15
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    Suggestion: reformulate your question to make it easier to understand. The term "relativity of simultaneity" is unclear. Also the term "selected" is paragraph 2 is unclear. – ben75 Dec 21 '18 at 8:02
  • The Coordinator's "relativity of simultaneity" = double-spend DoS Attacks – Long Field Jan 10 at 10:21
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The time to propagate a transaction through gossip is orders of magnitude smaller that the time required to accumulate a significant cumulative weight (so that it start to be relevant to look at the confirmation confidence).

Therefore the information-delta (i.e. the difference between the Tangle from node A and Tangle from B) is negligible when computing confirmation confidence.

To convince yourself, just send a transaction, measure the time it takes to be visible on thetangle.org, and measure the time it take to have a significant amount approvers.

In other word, your following assumption:

In one node the transaction T1 might be decided to take precedence. In another node, at the same time, T2 might be decided to take precedence. On top of that, a few moments later, each node might still come to a different conclusion.

can be truth for very young transactions, but as soon as a transaction start to accumulate significant weight (i.e. confirmation confidence >> 50%) : the confirmation confidence on node A and node B will converge.

To answer your question: "the 'Relativity of simultaneity' in observing the best confirmed double-spend" don't need to be resolved, because it is not a problem.

  • (1) How old is a 'very young transaction'? (2) After what time has a "transaction start to accumulate significant weight"? Do you have any statistics or numbers to show what those times might look like in real life? – The Coordinator Dec 22 '18 at 14:16
  • You say it is not a problem. Is that true? Are there no users that have brought up evidence of this issue in other forums or here on stackexchange? I did a search and there are many situations which this could explain. I am not saying it is a problem, only that it might be. But you are saying it isn't a problem - proof? Just search "not confirmed" here and surely some of these questions and answers are dealt with according to this potential issue. iota.stackexchange.com/search?q=not+confirmed – The Coordinator Dec 22 '18 at 14:22
  • Is the "information-delta" negligible in practice, historically, in the network? I'm interested to see what proof you have of this. – The Coordinator Dec 22 '18 at 14:25
  • Logically, though, since you say "time to propagate a transaction through gossip is orders of magnitude smaller that the time required to accumulate a significant cumulative weight" then it is in fact very possible to interfere in the network consensus by quickly attaching new transactions to bias the outcome. No? – The Coordinator Dec 22 '18 at 14:27

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