That is nearly two hundred lines of quite complex code. What results are you expecting and what results are you getting?

I've just tried running it under Python 3.3 and 3.5 on a RedHat-based Linux, and after generating a large amount of output (271315 lines, including "IMPOSSIBLE CONDITION OCCURED!" 552 times) it raised KeyError.

I then tried again on an Ubuntu-based Linux, and got the same result.

Can you demonstrate the same problem with a smaller, simpler example? What reasons do you have for believing that this is caused by "wrong caching of values"? What values do you think are being cached, and where?

You say:

"Comparisons fail, although they logically need to succeed."

Which comparisons? Can you isolate those failing comparisons without all the extraneous code?

"Integers magically increase without ever being written to in the code after initially assigned in the constructor."

Which integers? What evidence do you have that they are changing?

Bottom line is, while it is conceivable that you've found an interpreter bug that exists in at least three versions of Python, going back many years, that nobody has noticed before, I think it is far more likely that the bug is in your code. I'm going to close this ticket for now, but if you have answers for my questions and good evidence of an interpreter bug (preferably with a short and simple demonstration, see http://sscce.org/) please feel free to re-open it.

Thank you.