Verbal subgroup of finite type
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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]
Definition
Suppose is a group and is a subgroup of . We say that is a verbal subgroup of finite type in if the following equivalent conditions hold:
- There exists a single word in letters for some positive integer such that is the image of the word map corresponding to .
- There exists a finite collection of words (each with letters) such that is the union of the images of the word maps .
Relation with other properties
Stronger properties
| Property | Meaning | Proof of implication | Proof of strictness (reverse implication failure) | Intermediate notions |
|---|---|---|---|---|
| finite verbal subgroup | |FULL LIST, MORE INFO | |||
| verbal subgroup of finite group | |FULL LIST, MORE INFO |
Weaker properties
| Property | Meaning | Proof of implication | Proof of strictness (reverse implication failure) | Intermediate notions |
|---|---|---|---|---|
| verbal subgroup of finitely generated type | generated by a finite collection of words | |FULL LIST, MORE INFO | ||
| verbal subgroup | generated by a collection of words | |FULL LIST, MORE INFO | ||
| fully invariant subgroup | invariant under all endomorphisms | (via verbal) | (via verbal) | |FULL LIST, MORE INFO |
| purely definable subgroup | definable in the pure theory of the group | |FULL LIST, MORE INFO | ||
| characteristic subgroup | invariant under all automorphisms | |FULL LIST, MORE INFO | ||
| normal subgroup | invariant under all inner automorphisms | |FULL LIST, MORE INFO |