No that's tech cost. Policy cost is dynamic, tech cost uses the ratchet method.
Policy uses the ratchet method because its exploitable (you can build up culture) [it was exploited in early builds when the per city cost was higher and # of policies was how you won cultural]
You know I find it interesting that five years after this game was released people are still debating how the basic mechanics of it works.
Well it's a big game and only some of this can be gleaned from lua files etc. A lot of it you'd have to decompile the code to assembly language which would be a pain to go through trying to find something. So you're stuck with detailed observation of what happens in games and not everyone wants to do that, a lot probably see something happen once or twice and base assumptions on that, I've done it though I don't post about them . And of course there have been changes as mentioned above which no doubt adds to the confusion.
Anything that isn't exposed in the XML layer is exposed in the DLL code written in C, so knowledge of assembly not needed. However to get this you have to either download the DLL or alternatively download a mod that included DLL changes.
Note that the main things in lua are map scripts and user interface, but in at least one case it is known that logic that should have been in the back end was instead written in the user interface.
For more details, most of the knowledge is in Creation & Customization.
Well it's a big game and only some of this can be gleaned from lua files etc. A lot of it you'd have to decompile the code to assembly language which would be a pain to go through trying to find something. So you're stuck with detailed observation of what happens in games and not everyone wants to do that, a lot probably see something happen once or twice and base assumptions on that, I've done it though I don't post about them . And of course there have been changes as mentioned above which no doubt adds to the confusion.
I think the issue is that the basic mechanics are not clearly made available to the players (in part of the civilopedia)... not talking about things like AI behavior but basic game rules.
If it was written in C/C++ then it should have been compiled into machine code and hence would decompile into assembly language. If it was written in .net then it can be decompiled to a higher level, but that still is going to leave you with a lot of undocumented code to sort through.
Firaxis has provided the DLL as C/C++ source code as a separate download, you don't need to decompile the exe file.