In mathematics, in the field of group theory, a subgroup of a group is termed seminormal if there is a subgroup such that , and for any proper subgroup of , is a proper subgroup of .
This definition of seminormal subgroups is due to Xiang Ying Su... Foguel writes: "Su introduces the concept of seminormal subgroups and using this tool he gives four sufficient conditions for supersolvability."
Every normal subgroup is seminormal. For finite groups, every quasinormal subgroup is seminormal.
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