Universal graphs at the successor of a singular cardinal

Abstract

Abstract The paper is concerned with the existence of a universal graph at the successor of a strong limit singular μ of cofinality ℵ 0 . Starting from the assumption of the existence of a supercompact cardinal, a model is built in which for some such μ there are μ ++ graphs on μ + that taken jointly are universal for the graphs on μ + , while . The paper also addresses the general problem of obtaining a framework for consistency results at the successor of a singular strong limit starting from the assumption that a supercompact cardinal κ exists. The result on the existence of universal graphs is obtained as a specific application of a more general method.