Comparing inductive and circular definitions: parameters, complexity and games
Kai-Uwe Kühnberger, Benedikt Löwe, Michael Möllerfeld, Philip Welch

Abstract:
Gupta-Belnap-style circular definitions use all real numbers as
possible starting points of revision sequences. In that sense they are
boldface definitions. We discuss lightface versions of circular
definitions and boldface versions of inductive definitions.