like surd

A family R of l groups is considered as a subproduct radical class if R is clsoed under taking convex l subgroups, forming joins of convex l subgroups and forming direct products.

一组ｌ－群Ｕ称作一个子积根式类，如果它封闭于取凸ｌ－子群、作凸ｌ－子群的并及作完全次直积。