Abstract
One knows the classical problem of the embedding of a number field K in a field with class number one. This problem has a negative answer. In this article, we consider a new embedding problem: Is every number field contained in a Pólya field? A Pólya field is a number field K such that all the characteristic ideals In(K) are principal. We give a positive answer to this problem: the Hilbert class field HK of K is a Pólya field. However, HK is not necessarily the smallest Pólya field containing K. Thus, we give upper bounds for the Pólya number of K