2.1 Example 1

Let us consider the relation of equality. For example, $(2 = 2)$ , $\neg(2 = 3)$ , and etc. This relation is over $\mathbb{R}, \mathbb{R}$ . In other words, this relation $L \subseteq \mathbb{R} \times \mathbb{R}$ . To be more specific, $L = \{(x,x)\vert x \in \mathbb{R}\}$ .