Representation: x Rp c & y Rp d -> (x=y<->c=d)lV. Representatives: x Rp c -> atom(x)V. Null: Exist! x. (Exist c. x Rp c & c is atomless).A Set is an atom that uniquely represents a collection of atoms orabsence of atoms.Def.) Set(x) <-> Exist c. (c is a collection of atoms or c isatomless) & x Rp c & atom(x)Here in this theory because of lV there is no need to mention atom(x)in the above definitio