Hello Stephan
I conceived a method for how a digital PoS currency could possibly have a 10 second average transaction time, if it had a block time of 1 minute. I wrote about this on r/BlackCoin before you published your whitepaper. Adam Kryskow of the BlackCoin Foundation has since told me that my method is essentially the same is your. From what I understand of yours, that is the case. However, I envisioned a much simpler and mush less powerful implementation than your sub-second proposal.
I did this shortly after I became interested in BlackCoin. I came up with the idea of how to implement it after I read the Follow the Coin article at the link below were rat4 and Soepkip are interviewed, and the 10 second transaction time of BlackCoin is prominently mentioned in that article dated April 4th 2014.
http://www.followthecoin.com/interview-creator-blackcoin-bc/Since BlackCoin has a 1 minute block time, the minimum average transaction time should be 30 seconds.
The methodology that I foresaw is made possible by the fact that all of the nodes are cooperating, which is not possible with a PoW coin like Bitcoin. Therefore, whenever nodes with 51% of the stake at the start of a block have eventually confirmed that a transaction can be in the current block, it can be confirmed to the entire network that it will eventually be in the block. If an attempt at a double spend is occurring in the block, then the first node that subsequently becomes aware of the attempt should immediately ensure that second spend will not be added to the current block by sending an immediate alert that a double spend has been attempted. Each node receiving this alarm should verify that it is accurate. If it is a false claim, the offending node should be blackballed.
I assumed that this method was being programmed by rat4 when it was announced on r/BlackCoin that he was working on PoS 2.0 based on the Peercoin protocol.
It had never been adequately explained to me why Soepkip and others who should have known better had allowed the 10 second fiction to continue after the big pump and dump occurred shortly after the article came out. The 10 second claim was certainly used during that pump. I have tried on several occasions to get an explanation, but I have not tried recently to get one directly from Soepkip because all of my earlier attempts had been brushed aside by him.
I subsequently found out that that is not what rat4 is working on. That is when Alan told me that your scheme is a more sophisticated version of mine that assumes that the master nodes are sitting astride the backbones of the internet.
With regard to jubalixs question, it is my understanding that NXT, as it is written now does not incorporate this methodology. However, I could be wrong. Nevertheless, the cat is now out of the bag. IMO it will not be long before the NXT community understands how to modify their protocol and set out to do it. I would think that their first step would be to implement a simplified, bare bones version like my proposed version to determine in practice what kind of actual average transaction times can be achieved. The next step would be your Internet backbone version.
What Alan refers to as our internal discussions at the Blackcoin Foundation has just been within one relatively small committee where there is much resistance to rocking the Bitcoin boat and a realization that we do not have the ability to properly fund such a project at this time. However, I am sure that NXT does, if the initial investors think it is worthwhile, which I do not see why they would not.
RSchexnayder