Powering-invariant not implies divisibility-closed

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This article gives the statement and possibly, proof, of a non-implication relation between two subgroup properties. That is, it states that every subgroup satisfying the first subgroup property (i.e., powering-invariant subgroup) need not satisfy the second subgroup property (i.e., divisibility-invariant subgroup)
View a complete list of subgroup property non-implications | View a complete list of subgroup property implications
Get more facts about powering-invariant subgroup|Get more facts about divisibility-invariant subgroup

EXPLORE EXAMPLES YOURSELF: View examples of subgroups satisfying property powering-invariant subgroup but not divisibility-invariant subgroup|View examples of subgroups satisfying property powering-invariant subgroup and divisibility-invariant subgroup

Statement

It is possible to have a group G and a subgroup H

Proof

Proof idea

The key fact is that any finite subgroup of a group must be powering-invariant, but it need not be divisibility-invariant. We will construct an example where the subgroup is finite.

Proof details

For any prime number p, let G be the p-quasicyclic group. Let H be the subgroup comprising the elements of order 1 or p. Clearly, H, being finite, is powering-invariant (in fact, both G and H are powered over precisely the set of primes other than p). However, H is not divisibility-invariant: G is p-divisible, but H is not.