  This note reviews Section 2 of Dung's seminal 1995 paper on abstract
argumentation theory. In particular, we clarify and make explicit all of the
proofs mentioned therein, and provide more examples to illustrate the
definitions, with the aim to help readers approaching abstract argumentation
theory for the first time. However, we provide minimal commentary and will
refer the reader to Dung's paper for the intuitions behind various concepts.
The appropriate mathematical prerequisites are provided in the appendices.
