翻訳と辞書 |
Finitely generated group : ウィキペディア英語版 | Finitely generated group
In algebra, a finitely generated group is a group ''G'' that has some finite generating set ''S'' so that every element of ''G'' can be written as the product of finitely many elements of the finite set ''S'' and of inverses of such elements. Every finite group is finitely generated, since ''S'' can be taken to be ''G'' itself. Every infinite finitely generated group must be countable. A group that is generated by a single element is called cyclic. Every infinite cyclic group is isomorphic to the additive group of the integers Z. The additive group of rational numbers Q, while countable, is not finitely generated. ==Quotients and subgroups== Every quotient of a finitely generated group is finitely generated. However, a subgroup of a finitely generated group need not be finitely generated. For example, the commutator subgroup of the free group ''F''2 on two generators is not finitely generated. However, a subgroup of finite index in a finitely generated group is always finitely generated, and the Schreier index formula gives a bound on the number of generators required.〔Rose 2012, p. 55〕
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「Finitely generated group」の詳細全文を読む
スポンサード リンク
翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|