Currently, we do not need any measure of acceptance of a transaction, since the coordinator issues milestones, which provides us a simple rule to decide whether a transaction should or should not be accepted. But what would happen after the coordicide (what we are calling the death of the coordinator)? For this purpose, the confirmation confidence (which will be called CC hereafter) was defined in the Whitepaper as a post-coordicide metric of a transaction’s acceptance by the nodes. In this post, we will present how this metric’s behaviour depend on the parameter ɑ of the tip selection algorithm.
The CC of a certain transaction is obtained by releasing a large number of random walks and counting how many of these walks end on a tip that references the transaction. The fraction of tips which references it will be its CC. So, if a certain transaction has a CC close to 1, the recipient of the funds should be confident that he will be able to spend them later. Additionally, if the user knows how the CC of a normal, healthy transaction looks like, he might infer if his transaction is maturing normally. To illustrate this, let us consider a hypothetical situation in this post-coordicide scenario, where our default measure of acceptance of a transaction is the CC. You own a bookstore and a customer wants to buy a book paying in IOTAs. Two seconds after the payment the CC of the transaction is 1%. Does it mean that the buyer is trying to trick you? The answer is quite intuitive for anyone that has already used cryptocurrencies: No, since the transaction is not mature enough to get to any conclusion. However, in a healthy Tangle, the CC should increase fast. Now, suppose that, the next morning, the transaction’s CC it is still at 10%. In this case, you should start worrying, because the transaction is too old to have such a low CC. So it is clear that the CC of a transaction is a dynamic property which must be analyzed taking into account the transaction’s age. Continue on medium.com