On Small Iwasawa Invariants and Imaginary Quadratic Fields
نویسندگان
چکیده
If p is an odd prime that does not divide the class number of the imaginary quadratic field k , and the cyclotomic Z -extension of k has A-invariant less than or equal to two, we prove that every totally ramified Z extension of k has //-invariant equal to zero and A-invariant less than or equal to two. Combined with a result of Bloom and Gerth, this has the consequence that ß = 0 for every Z -extension of k , under the same assumptions. In the principal case under consideration, Iwasawa's formula for the power of p in the class number of the «th layer of a Z -extension becomes valid for all n , and is completely explicit.
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