. . . . . . "The study of recursive progressions of theories"@en . . "Efforts centered on the characterization, by means of recursive progressions of theories, of various stratifications of athematical proof, such as finitist, classical number-theoretical, predicative, etc. This as paired with the study, by means of hierarchies, of various stratifications of mathematical notions, such as finitist function, effective function, predicative set, etc. In an expansion of the original proposal, tho e parts of mat ematics which are needed in a systematic study of the notion of proof were considered; in particular intuitionism, which takes the concept of constructive proof as its basic subject matter. (Author)."@en . . . . . "Series(mathematics)" . . "Functions(mathematics)" . . "STANFORD UNIV CALIF APPLIED MATHEMATICS AND STATISTICS LABS." . . "Metamathematics." . . "Mathematical logic." . .