Degree of the Product of Two Algebraic Numbers One of Which Is of Prime Degree

Let <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>α</mi></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML"...

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Main Author: Paulius Virbalas
Format: Article
Language:English
Published: MDPI AG 2023-03-01
Series:Mathematics
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Online Access:https://www.mdpi.com/2227-7390/11/6/1485
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author Paulius Virbalas
author_facet Paulius Virbalas
author_sort Paulius Virbalas
collection DOAJ
description Let <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>α</mi></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>β</mi></semantics></math></inline-formula> be two algebraic numbers such that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mo>)</mo><mo>=</mo><mi>m</mi></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>β</mi><mo>)</mo><mo>=</mo><mi>p</mi></mrow></semantics></math></inline-formula>, where <i>p</i> is a prime number not dividing <i>m</i>. This research is focused on the following two objectives: to discover new conditions under which <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mi>β</mi><mo>)</mo><mo>=</mo><mi>m</mi><mi>p</mi></mrow></semantics></math></inline-formula>; to determine the complete list of values <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mi>β</mi><mo>)</mo></mrow></semantics></math></inline-formula> can take. With respect to the first question, we find that if the minimal polynomial of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>β</mi></semantics></math></inline-formula> over <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="double-struck">Q</mi></semantics></math></inline-formula> is neither <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>x</mi><mi>p</mi></msup><mo>+</mo><mi>c</mi></mrow></semantics></math></inline-formula> nor <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mi>c</mi><mi>x</mi><mo>+</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></semantics></math></inline-formula>, then necessarily <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mi>β</mi><mo>)</mo><mo>=</mo><mi>m</mi><mi>p</mi></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>α</mi><mi>β</mi></mrow></semantics></math></inline-formula> is a primitive element of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="double-struck">Q</mi><mo>(</mo><mi>α</mi><mo>,</mo><mi>β</mi><mo>)</mo></mrow></semantics></math></inline-formula>. This supplements some earlier results by Weintraub. With respect to the second question, we determine that if <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo>></mo><mn>2</mn></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo>−</mo><mn>1</mn></mrow></semantics></math></inline-formula> divides <i>m</i>, then for every divisor <i>k</i> of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo>−</mo><mn>1</mn></mrow></semantics></math></inline-formula>, there exist <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>α</mi></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>β</mi></semantics></math></inline-formula> such that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mi>β</mi><mo>)</mo><mo>=</mo><mi>m</mi><mi>p</mi><mo>/</mo><mi>k</mi></mrow></semantics></math></inline-formula>.
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spelling doaj.art-90ba6c6f2a1f4f7daf0a53a4f86d10dc2023-11-17T12:29:18ZengMDPI AGMathematics2227-73902023-03-01116148510.3390/math11061485Degree of the Product of Two Algebraic Numbers One of Which Is of Prime DegreePaulius Virbalas0Institute of Mathematics, Faculty of Mathematics and Informatics, Vilnius University, Naugarduko 24, LT-03225 Vilnius, LithuaniaLet <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>α</mi></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>β</mi></semantics></math></inline-formula> be two algebraic numbers such that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mo>)</mo><mo>=</mo><mi>m</mi></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>β</mi><mo>)</mo><mo>=</mo><mi>p</mi></mrow></semantics></math></inline-formula>, where <i>p</i> is a prime number not dividing <i>m</i>. This research is focused on the following two objectives: to discover new conditions under which <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mi>β</mi><mo>)</mo><mo>=</mo><mi>m</mi><mi>p</mi></mrow></semantics></math></inline-formula>; to determine the complete list of values <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mi>β</mi><mo>)</mo></mrow></semantics></math></inline-formula> can take. With respect to the first question, we find that if the minimal polynomial of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>β</mi></semantics></math></inline-formula> over <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi mathvariant="double-struck">Q</mi></semantics></math></inline-formula> is neither <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>x</mi><mi>p</mi></msup><mo>+</mo><mi>c</mi></mrow></semantics></math></inline-formula> nor <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mi>c</mi><mi>x</mi><mo>+</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></semantics></math></inline-formula>, then necessarily <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mi>β</mi><mo>)</mo><mo>=</mo><mi>m</mi><mi>p</mi></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>α</mi><mi>β</mi></mrow></semantics></math></inline-formula> is a primitive element of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="double-struck">Q</mi><mo>(</mo><mi>α</mi><mo>,</mo><mi>β</mi><mo>)</mo></mrow></semantics></math></inline-formula>. This supplements some earlier results by Weintraub. With respect to the second question, we determine that if <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo>></mo><mn>2</mn></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo>−</mo><mn>1</mn></mrow></semantics></math></inline-formula> divides <i>m</i>, then for every divisor <i>k</i> of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>p</mi><mo>−</mo><mn>1</mn></mrow></semantics></math></inline-formula>, there exist <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>α</mi></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>β</mi></semantics></math></inline-formula> such that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo form="prefix">deg</mo><mo>(</mo><mi>α</mi><mi>β</mi><mo>)</mo><mo>=</mo><mi>m</mi><mi>p</mi><mo>/</mo><mi>k</mi></mrow></semantics></math></inline-formula>.https://www.mdpi.com/2227-7390/11/6/1485degree of an algebraic numberGalois theorytransitive permutation groups
spellingShingle Paulius Virbalas
Degree of the Product of Two Algebraic Numbers One of Which Is of Prime Degree
Mathematics
degree of an algebraic number
Galois theory
transitive permutation groups
title Degree of the Product of Two Algebraic Numbers One of Which Is of Prime Degree
title_full Degree of the Product of Two Algebraic Numbers One of Which Is of Prime Degree
title_fullStr Degree of the Product of Two Algebraic Numbers One of Which Is of Prime Degree
title_full_unstemmed Degree of the Product of Two Algebraic Numbers One of Which Is of Prime Degree
title_short Degree of the Product of Two Algebraic Numbers One of Which Is of Prime Degree
title_sort degree of the product of two algebraic numbers one of which is of prime degree
topic degree of an algebraic number
Galois theory
transitive permutation groups
url https://www.mdpi.com/2227-7390/11/6/1485
work_keys_str_mv AT pauliusvirbalas degreeoftheproductoftwoalgebraicnumbersoneofwhichisofprimedegree