But whereas the French had analysed set-theoretical constructions carried out with the help of the Axiom of Choice, Luzin went considerably further and considered difficulties arising within the theory of effective sets.
Ngunit kung saan ang French had analysed-set-panteorya constructions natupad sa tulong ng Axiom of Choice, Luzin nagpunta malaki pa at itinuturing na problema na nagmula sa loob ng teorya ng epektibong sets.