Introverted Thinking is this: a is true because b is true because c is true because d is true etc..
Introverted Thinking is structure: pure, unadulterated structure. It only has to do with math in as much as it can structure sequences of Extraverted Thinking relationships between numbers.
Introverted Thinking says that something is true because something else is true. If you were to take this to its logical conclusion, then the world is true because everything in it is true.
"I think, therefore I am."
Anything else is not Introverted Thinking, but rather Introverted Thinking accompanied by another function. Most people don't know the difference, nor can you if you do not accept exertion theory as true. (there again, Introverted Thinking)
You might say that Introverted Thinking truths are only true because they are interconnected by Extraverted Thinking. But the two are probably inseperable.