Definition 5.34 (Equivalence Relations)

#Definition

An $equivalence relation$ is a binary relation, that is reflexive, transitive and symmetric

Example

Let $R : = {(a, b) | a = b o r a = - b}$
Let $L$ be the relation over all first names of students in this class (transcribed in English), where two names $x$ and $y$ are in $L$ , if $x$ and $y$ have the same number of letters.