Department of Mathematics, University of California, Irvine, California 92697 ; CNRS, Université Paris VII, 2 Place Jussieu, 75251 Paris Cedex 05, Paris, France
Abstract:
This paper establishes a refinement of the classical Löwenheim-Skolem theorem. The main result shows that any first order structure has a countable elementary substructure with strong second order properties. Several consequences for Singular Cardinals Combinatorics are deduced from this.