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<a accesskey="3" href="page.php?w=Lie_algebra_extension&amp;p=2">3.Next</a>
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<p>In the theory of <a href="page.php?w=Lie_group">Lie group</a>s, <a href="page.php?w=Lie_algebra">Lie algebra</a>s and <a href="page.php?w=Lie_algebra_representation">their representation theory</a>, a <b>Lie algebra extension</b>  is an enlargement of a given Lie algebra  by another Lie algebra . Extensions arise in several ways. There is the <b>trivial extension</b> obtained by taking a direct sum of two Lie algebras. Other types are the <b>split extension</b> and the <b>central extension</b>. Extensions may arise naturally, for instance, when</p><p>
<a accesskey="3" href="page.php?w=Lie_algebra_extension&amp;p=2">3.Next</a>
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