A D18: Map $f : X \to Y$ is strictly monotone with respect to $P_X$ and $P_Y$ if and only if one of the following statements is true
(1) | $\forall \, x, y \in X \, ((x, y) \in {\prec_X} \quad \Rightarrow \quad (f(x), f(y)) \in {\prec_Y})$ (D430: Strictly isotone map) |
(2) | $\forall \, x, y \in X \, ((x, y) \in {\prec_X} \quad \Rightarrow \quad (f(y), f(x)) \in {\prec_Y})$ (D431: Strictly antitone map) |