Verbally closed 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
Suppose is a group and is a subgroup of . We say that is verbally closed in if the following is true: For any word in letters, the image of under the word map corresponding to equals the intersection of with the image of under the word map corresponding to .
Relation with other properties
Stronger properties
| Property | Meaning | Proof of implication | Proof of strictness (reverse implication failure) | Intermediate notions |
|---|---|---|---|---|
| retract | |FULL LIST, MORE INFO | |||
| direct factor | (via retract) | (via retract) | |FULL LIST, MORE INFO |
Weaker properties
| Property | Meaning | Proof of implication | Proof of strictness (reverse implication failure) | Intermediate notions |
|---|---|---|---|---|
| local divisibility-closed subgroup | if an element of the subgroup has a root in the whole group, there is a root in the subgroup. | |FULL LIST, MORE INFO | ||
| divisibility-closed subgroup | if every element of the group has a root, every element of the subgroup has a root in the subgroup. | (via local divisibility-closed) | (via local divisibility-closed) | |FULL LIST, MORE INFO |
| local powering-invariant subgroup | if an element of the subgroup has a unique root in the group, that root is in the subgroup. | (via local divisibility-closed) | (via local divisibility-closed) | |FULL LIST, MORE INFO |
| powering-invariant subgroup | (via divisibility-closed) | (via divisibility-closed) | |FULL LIST, MORE INFO |