**canonical empty map**if and only if

(1) | $X = \emptyset$ |

(2) | $Y = \emptyset$ |

▾ Set of symbols

▾ Alphabet

▾ Deduction system

▾ Theory

▾ Zermelo-Fraenkel set theory

▾ Set

▾ Binary cartesian set product

▾ Binary relation

▾ Map

▾ Empty map

▾ Alphabet

▾ Deduction system

▾ Theory

▾ Zermelo-Fraenkel set theory

▾ Set

▾ Binary cartesian set product

▾ Binary relation

▾ Map

▾ Empty map

Formulation 0

A D1104: Binary relation structure $M = (X \times Y, f)$ is a **canonical empty map** if and only if

(1) | $X = \emptyset$ |

(2) | $Y = \emptyset$ |