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In mathematics, more specifically in topological groups, an extension of topological groups, or a topological extension, is a short exact sequence where and are topological groups and and are continuous homomorphisms which are also open onto their images. Every extension of topological group is therefore a group extension ==Classification of extensions of topological groups== We say that the topological extensions : and : are equivalent (or congruent) if there exists a topological isomorphism making commutative the diagram of Figure 1. We say that the topological extension : is a ''split extension'' (or splits) if it is equivalent to the trivial extension : where is the natural inclusion over the first factor and is the natural projection over the second factor. It is easy to prove that the topological extension splits if and only if there is a continuous homomorphism such that is the identity map on Note that the topological extension splits if and only if the subgroup is a topological direct summand of 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Extension of a topological group」の詳細全文を読む スポンサード リンク
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