Pseudoverbal subgroup

From Groupprops

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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 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