Group in which every automorph-conjugate subgroup is characteristic

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This article defines a group property: a property that can be evaluated to true/false for any given group, invariant under isomorphism
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The version of this for finite groups is at: finite ACIC-group

Definition

A group is termed a 'group in which every automorph-conjugate subgroup is characteristic if it satisfies the following equivalent conditions:

Formalisms

In terms of the subgroup property collapse operator

This group property can be defined in terms of the collapse of two subgroup properties. In other words, a group satisfies this group property if and only if every subgroup of it satisfying the first property (automorph-conjugate subgroup) satisfies the second property (characteristic subgroup), and vice versa.
View other group properties obtained in this way

The property of being an ACIC-group can be viewed as the collapse:

Automorph-conjugate subgroup = Characteristic subgroup

Relation with other properties

Stronger properties

Weaker properties

Metaproperties

Metaproperty Satisfied? Proof Statement with symbols
subgroup-closed group property No ACIC is not subgroup-closed It is possible to have a group G and a subgroup H of G such that G is ACIC but H is not ACIC.
quotient-closed group property No ACIC is not quotient-closed It is possible to have a group G and a normal subgroup H of G such that G is ACIC but the quotient group G/H is not ACIC.
normal subgroup-closed group property No ACIC is not normal subgroup-closed It is possible to have a group G and a normal subgroup H of G such that G is ACIC but H is not ACIC.
finite direct product-closed group property No ACIC is not finite direct product-closed It is possible to have groups G_1 and G_2 such that both G_1 and G_2 are ACIC but the external direct product G_1 \times G_2 is not ACIC.
characteristic subgroup-closed group property Yes ACIC is characteristic subgroup-closed Suppose G is an ACIC-group and H is a characteristic subgroup of G. Then, H is also an ACIC-group.
characteristic quotient-closed group property Yes ACIC is characteristic quotient-closed Suppose G is an ACIC-group and H is a characteristic subgroup of G. Note that, since characteristic implies normal, it makes sense to talk of the quotient group G/H. This quotient group must also be ACIC.

Testing

GAP code

One can write code to test this group property in GAP (Groups, Algorithms and Programming), though there is no direct command for it.
View other GAP-codable group properties | View group properties with in-built commands

The following GAP code can be used to check whether a group is ACIC:

AutomorphicImage := function(a,K)
		 local L, g;
		 L := List([]);
		 for g in Set(K) do
		     Add(L,g^a);
		 od;
		 return Group(L);
end;;

IsAutomorphConjugateSubgroup := function(G,H)
		     local A, s;
		     A := AutomorphismGroup(G);
		     for s in A do
		     	 if not (AutomorphicImage(s,H) in ConjugateSubgroups(G,H)) then
			    return false;
			    fi;
			 od;
		     return true;
end;;

IsACIC := function(G)
       local H;
       if IsAbelian(G) then return true; fi;
       for H in List(ConjugacyClassesSubgroups(G),Representative) do
       	   if IsAutomorphConjugateSubgroup(G,H) and not IsNormal(G,H) then return false; fi;
od;
	return true;
end;;

To do the test, enter:

IsACIC(G)

where G is the group that needs to be tested. The code works only for finite groups, and as such, is extremely inefficient.