Relation

• Relation #Card
  • A relation $R$ between sets $X$ and $Y$ is a subset of the Cartesian product $X \times Y$. - We write $xRy \iff (x, y) \in R$.

Back

A relation $R$ between sets $X$ and $Y$ is a subset of the Cartesian product $X \times Y$.

• We write $xRy \iff (x, y) \in R$.

Lean

Rel X Y := X → Y → Prop（本ノートでは Set (X × Y) として扱う）