Classification Theory. Second Edition with a new introduction

Focusing on the nuances of complete first-order theories, this book explores the distinctions between understandable and complex theories, primarily those that are countable. It builds on foundational concepts such as first-order logic, Gödel's completeness theorem, and naive set theory, making it suitable for readers with a background in model theory. By examining these dividing lines, the text aims to enhance the reader's understanding of the structure and nature of these mathematical theories.