Putnam's theorem on the complexity of models

Warren Goldfarb

pp. 45-50

in: Geoffrey Hellman, Roy T. Cook (eds), Hilary Putnam on logic and mathematics, Berlin, Springer, 2018

Abstract

A streamlined proof of a theorem of Putnam's: any satisfiable schema of predicate calculus has a model in which the predicates are interpreted as Boolean combinations of recursively enumerable relations. Related open problems are canvassed.