Hereditarily normal subgroup
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This article defines a subgroup property: a property that can be evaluated to true/false given a group and a subgroup thereof, invariant under subgroup equivalence. View a complete list of subgroup properties[SHOW MORE]
This article describes a property that arises as the conjunction of a subgroup property: transitively normal subgroup with a group property (itself viewed as a subgroup property): Dedekind group
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A subgroup of a group is termed hereditarily normal (sometimes, quasicentral) if every subgroup of it is normal in the whole group.
Definition with symbols
A subgroup of a group is termed hereditarily normal (sometimes, quasicentral) if for any subgroup , is normal in .
In terms of the hereditarily operator
This property is obtained by applying the hereditarily operator to the property: normal subgroup
View other properties obtained by applying the hereditarily operator
The property of being hereditarily normal is a result of applying the hereditarily operator on the property of normality.
Relation with other properties
- Transitively normal subgroup
- Hereditarily permutable subgroup
- Hereditarily subnormal subgroup
- Hereditarily pronormal subgroup
- Normal subgroup
This subgroup property is left-hereditary: any subgroup of a subgroup with this property also has this property. Hence, it is also a transitive subgroup property.
Since the left-hereditarily operator is idempotent, the property of being hereditarily normal is itself left hereditary (that is, every subgroup of a hereditarily normal subgroup is hereditarily normal).
Note that being a left-hereditary property, it is automatically transitive and also intersection-closed.
YES: This subgroup property satisfies the transfer condition: if a subgroup has the property in the whole group, its intersection with any subgroup has the property in that subgroup.
View other subgroup properties satisfying the transfer condition
Since normality satisfies the intermediate subgroup condition, and the left-hereditarily operator preserves the intermediate subgroup condition, the property of being hereditarily normal also satisfies the transfer. condition. Hence it also satisfies the intermediate subgroup condition.
The trivial group is obviously hereditarily normal.