Published online by Cambridge University Press: 22 January 2016
Let p be an odd prime and d be a positive integer prime to p such that d ≢ 2 mod 4. For technical reasons, we also assume that . For each integer n ≥ 1, we choose a primitive nth root ζn of 1 so that
whenever n | m. Let
be its cyclotomic Zp-extension, where
is the nth layer of this extension. For n ≤ 1, we denote the Galois group Ga\(Kn/K0 ) by Gn , the unit group of the ring of integers of Kn by En , and the group of cyclotomic units of Kn by Cn . For the definition and basic properties of cyclotomic units such as the index theorem, we refer [6] and [7]. In this paper we examine the injectivity of the homomorphism
between the first cohomology groups induced by the inclusion Cn → En .