Automorph-dominating subgroup
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]
BEWARE! This term is nonstandard and is being used locally within the wiki. [SHOW MORE]
Definition
A subgroup of a group is termed an automorph-dominating subgroup if it satisfies the following equivalent conditions:
- For any automorphism of , there exists such that the automorph is contained in the conjugate subgroup .
- For any automorphism of , there exists such that the automorph contains the conjugate subgroup .
Note that the for version (2) may not equal the for version (1).
Note that if is a co-Hopfian group (i.e. it does not contain any proper subgroup isomorphic to it) this property is equivalent to being an automorph-conjugate subgroup.
Relation with other properties
Stronger properties
| Property | Meaning | Proof of implication | Proof of strictness (reverse implication failure) | Intermediate notions |
|---|---|---|---|---|
| endomorph-dominating subgroup | every image under an endomorphism is contained in a conjugate | (obvious) | follows from characteristic not implies fully invariant -- any characteristic subgroup that is not fully invariant will do | |FULL LIST, MORE INFO |
| homomorph-dominating subgroup | every image under a homomorphism is contained in a conjugate | (via endomorph-dominating) | (via endomorph-dominating) | |FULL LIST, MORE INFO |
| automorph-conjugate subgroup | every automorphic subgroup equals a conjugate | (obvious) | follows from endomorph-dominating not implies automorph-conjugate | |FULL LIST, MORE INFO |
| isomorph-dominating subgroup | every isomorphic subgroup is contained in a conjugate subgroup | |FULL LIST, MORE INFO |
Weaker properties
| Property | Meaning | Proof of implication | Proof of strictness (reverse implication failure) | Intermediate notions |
|---|---|---|---|---|
| closure-characteristic subgroup | normal closure is a characteristic subgroup | |FULL LIST, MORE INFO | ||
| core-characteristic subgroup | normal core is a characteristic subgroup | |FULL LIST, MORE INFO |