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On the parity of the class number of the field of q-th roots of unity. (English) Zbl 0703.11052
Kummer began investigations of the parity of the class number $$h_ q$$ of the cyclotomic field, $${\mathbb{Q}}(\zeta_ q)$$ of q-th roots of unity over the rationals where q is prime. Hasse refined Kummer’s results for imaginary cyclic extensions of $${\mathbb{Q}}$$. The author cites many references concerning work on the parity of the class numbers of Abelian fields (including that of the reviewer) as motivation for his research in this paper wherein he proves: If q and $$p=(q-1)/2$$ are primes with 2 being inert in $${\mathbb{Q}}(\zeta_ p+\zeta_ q^{-1})$$ then $$h_ q$$ is odd.
Reviewer: R.A.Mollin

##### MSC:
 11R18 Cyclotomic extensions 11R29 Class numbers, class groups, discriminants
##### Keywords:
parity; class number; cyclotomic field
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