ThmDex – An index of mathematical definitions, results, and conjectures.
Result R2076 on D529: Map inverse image
Inverse image of empty set
Formulation 0
Let $f : X \to Y$ be a D18: Map.
Let $\emptyset$ be the D13: Empty set.
Then \begin{equation} f^{-1}(\emptyset) = \emptyset \end{equation}