Characterization of Ricci Solitons and Harmonic Vector Fields on the Lie Group <i>Nil</i><sup>4</sup>

This study considers a left-invariant Riemannian metric <i>g</i> on the Lie group <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>N</mi><mi>i</mi><msup><mi&...

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Bibliographic Details
Main Authors: Yanlin Li, Ahmed Mohammed Cherif, Yuquan Xie
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Mathematics
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Online Access:https://www.mdpi.com/2227-7390/13/7/1155
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Summary:This study considers a left-invariant Riemannian metric <i>g</i> on the Lie group <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>N</mi><mi>i</mi><msup><mi>l</mi><mn>4</mn></msup></mrow></semantics></math></inline-formula>. We introduce a Ricci solitons’ classification on <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><mi>N</mi><mi>i</mi><msup><mi>l</mi><mn>4</mn></msup><mo>,</mo><mi>g</mi><mo>)</mo></mrow></semantics></math></inline-formula>. These are expansive non-gradient Ricci solitons. We examine the existence of harmonic maps into <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><mi>N</mi><mi>i</mi><msup><mi>l</mi><mn>4</mn></msup><mo>,</mo><mi>g</mi><mo>)</mo></mrow></semantics></math></inline-formula> from a compact Riemannian manifold. Additionally, we provide a characterization of a class of harmonic vector fields on <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><mi>N</mi><mi>i</mi><msup><mi>l</mi><mn>4</mn></msup><mo>,</mo><mi>g</mi><mo>)</mo></mrow></semantics></math></inline-formula>.
ISSN:2227-7390