A simplified functorial construction of the veblen hierarchy
Andreas Weiermann · Mathematical logic quarterly · 1993
Abstract We give a simple and elementary proof of the following result of Girard and Vauzeilles which is proved in [5]: “The binary Veblen function ψ: On × On — On is a dilator.” Our proof indicates the intimate connection between the traditional theory of ordinal notation systems and Girard's theory of denotation systems. MSC: 03F15.