P-constrained not implies p-solvable

From Groupprops

This article gives the statement and possibly, proof, of a non-implication relation between two group properties. That is, it states that every group satisfying the first group property (i.e., p-constrained group) need not satisfy the second group property (i.e., p-solvable group)
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Definition

It is possible to have a finite group G and a prime number p such that G is a p-constrained group but not a p-solvable group.

Related facts

Converse

Opposite facts

Proof

Let G be the wreath product of Z2 and A5 defined as the wreath product with base group cyclic group:Z2 and acting group alternating group:A5, where we use the natural permutation action of the acting group on a set of five elements. More explicitly, G is the external semidirect product of elementary abelian group:E32 and alternating group:A5 where the latter acts on the former by coordinate permutations induced by the permutations on a set of five elements.

The group G has order 2560=1920=2735

Let p=2.

We note that:

  1. G is p-constrained: Indeed, Op(G) is trivial, and Op,p(G) is the base of the semidirect product, i.e., a normal subgroup isomorphic to elementary abelian group:E32. In particular, this is contained in any p-Sylow subgroup P, so POp,p(G) is also the normal subgroup that forms the base of the semidirect product. The subgroup is a self-centralizing normal subgroup, because it is an abelian normal subgroup and the induced action by the quotient is faithful. Thus, we get the condition CG(POp,p(G))Op,p(G).
  2. G is not p-solvable: For this, note that alternating group:A5, the simple non-abelian composition factor of G, is neither a p-group nor a p-group.