Verbal subgroup of finite type

From Groupprops

BEWARE! This term is nonstandard and is being used locally within the wiki. [SHOW MORE]

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:

  1. There exists a single word in letters for some positive integer such that is the image of the word map corresponding to .
  2. 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