Pseudoverbal subgroup
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 subpseudovariety of the variety of groups, i.e., is a collection of groups closed under taking subgroups, quotients, and direct products. Equivalently, the group property of being in is a pseudovarietal group property.
The -pseudoverbal subgroup of a group is defined as the intersection of all normal subgroups of for which the quotient group is in . Note that the quotient group of by its -pseudoverbal subgroup need not itself be in the pseudovariety.
Relation with other properties
Stronger properties
| Property | Meaning | Proof of implication | Proof of strictness (reverse implication failure) | Intermediate notions |
|---|---|---|---|---|
| verbal subgroup | similar definition, but for a subvariety instead of a subpseudovariety | |FULL LIST, MORE INFO |
Weaker properties
| Property | Meaning | Proof of implication | Proof of strictness (reverse implication failure) | Intermediate notions |
|---|---|---|---|---|
| quotient-subisomorph-containing subgroup | contained in the kernel of any homomorphism to the quotient group | |FULL LIST, MORE INFO | ||
| fully invariant subgroup | (via quotient-subisomorph-containing) | (via quotient-subisomorph-containing) | |FULL LIST, MORE INFO | |
| characteristic subgroup | (via fully invariant) | (via fully invariant) | Fully invariant subgroup|FULL LIST, MORE INFO |