Set Theory & Logic

A \cap B = \{x : x \in A \land x \in B\}

A \cup B = \{x : x \in A \lor x \in B\}

\forall \varepsilon > 0,\; \exists \delta > 0 : |x - a| < \delta \implies |f(x) - f(a)| < \varepsilon

\mathbb{N} \subset \mathbb{Z} \subset \mathbb{Q} \subset \mathbb{R} \subset \mathbb{C}

|\mathbb{R}| = 2^{\aleph_0}