| (1) | $\forall \, x \in X : \forall \, y, y' \in Y \, ((x, y), (x, y') \in f \quad \Rightarrow \quad y = y')$ (D358: Right-unique binary relation) |
| (2) | $\forall \, x \in X : \exists \, y \in Y : (x, y) \in f$ (D359: Left-total binary relation) |
| (1) | $\forall \, x \in X : \forall \, y, y' \in Y \, ((x, y), (x, y') \in f \quad \Rightarrow \quad y = y')$ (D358: Right-unique binary relation) |
| (2) | $\forall \, x \in X : \exists \, y \in Y : (x, y) \in f$ (D359: Left-total binary relation) |