I have a couple of lessons in my book that I just don't get. They seem so abstract to me. Here is what it's about:
See the attachment:
Straight translation of the lesson name from my language to English would be
"Formal theories". I googled it, like i always do before bothering someone, but I can't find any example or a online book about it. It horribly explained in the book and I dont see any chance to learn it from just reading the book. Exam is nearing and I'de be thankfull to anyone that can point me to a book (free ofcourse ) on the internet or some useful site.