Left-transitively homomorph-containing not implies subhomomorph-containing

From Groupprops

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., left-transitively homomorph-containing subgroup) need not satisfy the second subgroup property (i.e., subhomomorph-containing subgroup)
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Proof

Let G be the direct product:

G:=A5×C2

where A5 is the alternating group of degree five and C2 is the cyclic group of order two. Let H be the first direct factor.

Then:

  • For any group K containing G as a homomorph-containing subgroup, K also contains H as a homomorph-containing subgroup: For any homomorphism α:HK, we can extend it to a homomorphism β:GK, since H is a direct factor of G. Since G is homomorph-containing in K, β(G)G, so α(H)G. Now, since H is homomorph-containing in G, α(H) is contained in H.
  • H is not a subhomomorph-containing subgroup of G: H has cyclic subgroups of order two, that are isomorphic to cyclic subgroups of order two in G and outside H.