On index divisors and monogenity of certain octic number fields defined by $x^8+ax^3+b$

UDC 511 For any octic number field $K$ generated by a root $\alpha$ of a monic irreducible trinomial $F(x)=x^8+ax^3+b \in \mathbb{Z}[x]$ and for every rational prime $p,$ we show when $p$ divides the index of $K.$  We also describe the prime power decomposition of the index...

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Datum:2024
1. Verfasser: Kchit, Omar
Format: Artikel
Sprache:Englisch
Veröffentlicht: Institute of Mathematics, NAS of Ukraine 2024
Online Zugang:https://umj.imath.kiev.ua/index.php/umj/article/view/7536
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Назва журналу:Ukrains’kyi Matematychnyi Zhurnal
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Ukrains’kyi Matematychnyi Zhurnal
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Zusammenfassung:UDC 511 For any octic number field $K$ generated by a root $\alpha$ of a monic irreducible trinomial $F(x)=x^8+ax^3+b \in \mathbb{Z}[x]$ and for every rational prime $p,$ we show when $p$ divides the index of $K.$  We also describe the prime power decomposition of the index $i(K).$ In this way, we give a partial answer to { Problem $22$} of Narkiewicz [Elementary and analytic theory of algebraic numbers, Springer-Verlag, Auflage (2004)] for this family of number fields. As an application of our results, we conclude that if $i(K)\neq1,$  then $K$ is not monogenic. We illustrate our results by some computational examples. 
DOI:10.3842/umzh.v76i7.7536