▾ Set of symbols
▾ Alphabet
▾ Deduction system
▾ Theory
▾ Zermelo-Fraenkel set theory
▾ Set
▾ Binary cartesian set product
▾ Binary relation
▾ Map
▾ Empty map
Canonical 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) $Y = \emptyset$