My point is this: the documentation is being misleading. The way it is written implies:
Edu_t = min{A_t,B_t,C_t}
That says the education index depends only on current information - t -, and it equals the lowest of the sub-indexes. That is obviously false.
Now, what I wrote is the lazy way of writing:
Edu_t = (min{A_t,B_t,C_t} + Edu_(t-1) + Edu_(t-2) + Edu_(t-3) + Edu_(t-4))/5
That says it depends on the current information - the smallest of the sub-index, and on the indexes of the previous four months, not five.
Why should this matter?
1. If someone comes up and says "I've taken the lowest of the three partial indexes, adding to it 4 times the current education index and dividing the result by 5, but I'm still getting the wrong number", they'll know why. It's not their fault, but they are doing it wrong.
2. The second one is more interesting, and concerns a bit of an odd fact if people think about it.
Someone looking at that might think "since the index depends on the four previous indexes, if I don't do anything and the targets don't move for fours months, the index should plateau in four months".
Actually, no. While the "oldest" factor is Edu_(t-4) in that equation, Edu_(t-4) itself depends on Edu_(t-5) to Edu_(t-8). Edu_(t-8) in its turn depends as far as Edu_(t-12). And so on ad infinitum.
So, Edu_t in fact depends on all previous information. So, when should the index plateau? To be precise, never. Luckily for us, the number of decimal places that can be store is finite, and hopefully small, so there are rounding errors that can bring the process to a stop.
As long it takes, depends on the precision with which numbers are stored, the magnitude of the changes, and the coeficientes, which I assume all to be 1. I imagine that if someone is building a country from a C3 and bringing the index to 200, it'll take some 5 to 6 game years for the index to settle, when all the sub-indexes are at 200.
The short and rough of it:
1. Re-write that bit about adding four times the current index.
2. The indexes take forever to reach their "true" value.