Resumen de On the construction of simple first-order formulae without recursive models
The paper is about solutions of the well known problems from Hilbert-Bernays whether every satisfiable closed formula of the restricted lower predicate calculus admits recursive models. Aanderaa's method is presented which associates formulae to register machine programs in such a way that the formula is the axiom of an essentially undecidable theory resp. satisfiable but without recursive models if the machine program enumerates two recursively inseparable sets. A simplification of Aanderaa's formulae brings their decision problems still closer to the corresponding stop problems of the machine programs and results in a more direct and technically less involved realization of the basic idea.[...]
