Lemma about the embedded segments. Mappings of sets

Mappings of sets

X = D_f — range of definition of mapping f

Totality y ∈ Y: ∃ x ∈ X, such, that y = f(x), denotes Imf or

Y_f — range of values of mapping;

y — image x by mapping f;

x — inverse image y by mapping f.