## Abstract For any plane graph __G__ the number of edges in a minimum edge covering of the faces of __G__ is at most the vertex independence number of __G__ and the numbre of vertices in a minimum vertex covering of the faces of __G__ is at most the edge independence number of __G__. © 1995 John W
A Note on Algebraic Γ-Monomials and Double Coverings
✍ Scribed by Soogil Seo
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 112 KB
- Volume
- 93
- Category
- Article
- ISSN
- 0022-314X
No coin nor oath required. For personal study only.
✦ Synopsis
We discuss algebraic C-monomials of Deligne. Deligne used the theory of Hodge Cycles to show that algebraic C-monomials generate Kummer extensions of certain cyclotomic fields. Das, using a double complex of Anderson and Deligne's results, showed that certain powers of algebraic C-monomials and certain square roots of sine monomials generate abelian extensions of Q. Das also gave one example of a nonabelian double covering of a cyclotomic field generated by the square root of a sine monomial. In this note, we will produce infinitely many examples of nonabelian double coverings of cyclotomic fields of Das type. The construction of the examples depends in an interesting way on a lemma of Gauss figuring in an elementary proof of quadratic reciprocity.
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