TY - JOUR

T1 - The lattice of subfields of a radical extension

AU - de Orozco, MariáAcosta

AU - Vélez, William Yslas

N1 - Funding Information:
author was supported, Research Grant.
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.

PY - 1982/12

Y1 - 1982/12

N2 - Let xm - a be irreducible over F with char F{does not divide}m and let α be a root of xm - a. The purpose of this paper is to study the lattice of subfields of F(α) F and to this end C( F(α) F, k) is defined to be the number of subfields of F(α) of degree k over F. C( F(α) F, pn) is explicitly determined for p a prime and the following structure theorem for the lattice of subfields is proved. Let N be the maximal normal subfield of F(α) over F and set n = |N : F|, then C( F(α) F, k) = C( F(α) F, (k, n)) = C( N F, (k, n)). The irreducible binomials xs - b, xs - c are said to be equivalent if there exist roots βs = b, γs = a such that F(β) = F(γ). All the mutually inequivalent binomials which have roots in F(α) are determined. Finally these results are applied to the study of normal binomials and those irreducible binomials x2e - a which are normal over F (char F ≠ 2) together with their Galois groups are characterized.

AB - Let xm - a be irreducible over F with char F{does not divide}m and let α be a root of xm - a. The purpose of this paper is to study the lattice of subfields of F(α) F and to this end C( F(α) F, k) is defined to be the number of subfields of F(α) of degree k over F. C( F(α) F, pn) is explicitly determined for p a prime and the following structure theorem for the lattice of subfields is proved. Let N be the maximal normal subfield of F(α) over F and set n = |N : F|, then C( F(α) F, k) = C( F(α) F, (k, n)) = C( N F, (k, n)). The irreducible binomials xs - b, xs - c are said to be equivalent if there exist roots βs = b, γs = a such that F(β) = F(γ). All the mutually inequivalent binomials which have roots in F(α) are determined. Finally these results are applied to the study of normal binomials and those irreducible binomials x2e - a which are normal over F (char F ≠ 2) together with their Galois groups are characterized.

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U2 - 10.1016/0022-314X(82)90040-3

DO - 10.1016/0022-314X(82)90040-3

M3 - Article

AN - SCOPUS:49049139651

VL - 15

SP - 388

EP - 405

JO - Journal of Number Theory

JF - Journal of Number Theory

SN - 0022-314X

IS - 3

ER -