## 3.1 Introduction

We need some set theory every now and then. We use Zermelo-Fraenkel set theory with the axiom of choice (ZFC) as described in [Kunen] and [Jech].

Comment #6007 by Laurent Moret-Bailly on

Perhaps it should be mentioned that ZFC also includes the axiom of foundation (called "regularity" by Jech).

Comment #6167 by on

ZF always includes foundation as far as I can tell.

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