文摘
For a real abelian field K, Sinnott?s group of circular units is a subgroup of finite index in the full group of units playing an important role in Iwasawa theory. Let be the cyclotomic -extension of K, and be the class number of , the n-th layer in . Then for and n going to infinity, the p-parts of the quotients stabilize. Unfortunately this is not the case for , when the group of all units of K, whose squares belong to , is usually used instead of . But is better only for index formula purposes, not having the other nice properties of . The main aim of this paper is to offer another alternative to which can be used in cyclotomic -extensions even for still keeping almost all nice properties of .