I personally don't think we (YACoin) should force people to keep their clients open all the time. And I am at a complete loss how POS is supposed to be some kind of security utopia, especially when POS it nearly killed us. We neutered POS at block 420000, so It's behaving itself nicely now.
From what I have read, the problem YAC had with POS is YAC (and its offsprings) specific. POS promises to offer solutions to problems with POW that will probably have pure POW coins killed. POS is very complex, however.
I think the problem is actually inherited from PPCoin. I seem to remember the code that calculate trust score in YAC was the same as what I saw in PPC (I'm not familiar with programming though
). The trust score issue just shows itself more clearly in YACoin because of wallet performance problems and having longer POW chains for POS block to orphan....
After mhps's comment I dug down into the code and came to the conclusion mhps was right. That is, a 1000 day old chunk of 100 coins will get get 1000 days worth of interest. And there is no limit to the number of days. If you don't open your client for 10 years, and YACoin is still around in 10 years, then you will get 10 years worth of interest.
However, the probability of finding a POS block for those 100 coins started at a low point at 30 days, and increased gradually until the coins got 90 days old. After 90 days the coin's continue to accrue interest, but the probability of finding a POS block for those coins stays at a constant maximum probability from day 90 until day 1000. If a POS block were found on day 1000, I would expect the interest to be (100)*(0.05)*(1000)/(365) or 13.698.
I've always assumed interest paid is capped at 90 days because that's what I heard about PPCoin. Thank you for going through the code to find out.
Does the probability of finding POS block increase linearly with days between 30 and 90 but is independent of the quantity of coins in the chunk?