scheme :: RELSET_1:sch 3
Sch3{ F₁() -> set , F₂() -> Subset of F₁(), F₃( object ) -> set } :

ex R being Relation of F₂() st
for i being Element of F₁() st i in F₂() holds
Im (R,i) = F₃(i)

provided

A1: for i being Element of F₁() st i in F₂() holds
F₃(i) c= F₂()