Half conformally flat pseudo-Riemannian neutral Lie groups of dimension four are studied and examples of cyclic Lie groups as well as naturally reductive cases are completely classified.

中文翻译：

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四维中性李群的自对偶与反自对偶

研究了四维的半共形平坦伪黎曼中性李群，并完全分类了循环李群的例子以及自然还原的例子。