Pólya-Ostrowski Group and Unit Index in Real Biquadratic Fields

Abstract

For a Galois number field K, Pólya-Ostrowski group of K is the subgroup of the ideal class group of K generated by all strongly ambiguous ideal classes. K is called a Pólya field, whenever its Pólya group is trivial. In this paper, using some results in [13,14], we give an explicit relation between order of Pólya groups and Hasse unit indices in real biquadratic fields.