Just-infinite群

群論中一個無限群G稱為just-infinite，如果G的所有真商群都是有限群，也就是說所有非平凡正規子群都有有限指數。

例子

無限循環群 $C_{\infty }$
無限二面體群 $D_{\infty }$
無限單群

參考

McCarthy, D., Infinite groups whose proper quotient groups are finite, I （页面存档备份，存于）. Communications on Pure and Applied Mathematics. 1968, 21(6):545–562.
McCarthy, D., Infinite groups whose proper quotient groups are finite, II （页面存档备份，存于）. Communications on Pure and Applied Mathematics. 1970, 23(5):767–789.

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