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Normal Structure and Characteristic Subgroups

Normal Structure and Characteristic Subgroups

Subsections

Characteristic Subgroups and Subgroup Series

Agemo(G, i) : GrpPC, RngIntElt -> GrpPC
Given a p-group G, return the characteristic subgroup of G generated by the elements x^(p^i), x in G, where i is a positive integer.
AbelianBasis(G) : GrpPC -> [ GrpPCElt ], [ RngIntElt ]
Given an abelian group G, return sequence B and I such that ( order)(B[i]) = I[i] and < B > = G and I are the types of each p-primary component of G.
AbelianInvariants(G) : GrpPC -> [RngIntElt]
The abelian invariants of the abelian group G as a sequence of integers.
Centre(G) : GrpPC -> GrpPC
Center(G) : GrpPC -> GrpPC
The centre of the group G.
ChiefSeries(G) : GrpPC -> [GrpPC]
A chief series for the group G. The series is returned as a sequence of subgroups of G.
Complements(G, H) : GrpPC, GrpPC -> [GrpPC]
Given a normal subgroup N of a group G, return conjugacy class representatives for the complements of N in G.
CompositionSeries(G) : GrpPC -> [GrpPC]
A composition series for the group G. The series is returned as a sequence of subgroups of G. The i-th term of the composition series has a presentation given by the generators G.i through G.NPCgens(G) and relations involving those generators only.
CompositionSeries(G, i) : GrpPC, RngIntElt -> [GrpPC]
The i + 1-th entry of the composition series for the group G. Its presentation given by the generators G.i + 1 through G.NPCgens(G) and relations involving those generators only.
DerivedLength(G) : GrpPC -> RngIntElt
The derived length of the group G.
DerivedSeries(G) : GrpPC -> [GrpPC]
The derived series of the group G. The series is returned as a sequence of subgroups.
DerivedSubgroup(G) : GrpPC -> GrpPC
DerivedGroup(G) : GrpPC -> GrpPC
The derived subgroup of the group G.
ElementaryAbelianSeries(G) : GrpPC -> [GrpPC]
An elementary abelian series is a chain of normal subgroups with the property that the quotient of each pair of successive terms in the series is elementary abelian. Thus, it refines the derived series. The elementary abelian series for the group G is returned as a sequence of subgroups.
FittingSubgroup(G) : GrpPC -> GrpPC
The Fitting subgroup of the group G.
FrattiniSubgroup(G) : GrpPC -> GrpPC
The Frattini subgroup of the group G.
Hypercentre(G) : GrpPC -> GrpPC
Hypercenter(G) : GrpPC -> GrpPC
The hypercentre of the group G, i.e. the stationary term in the upper central series for G.
JenningsSeries(G) : GrpPC -> [GrpPC]
Given a p-group G, return the Jennings series for G. The series is returned as a sequence of subgroups. The Jennings series J_1 triangleright J_2 triangleright ... triangleright J_i ... of a p-group G is defined inductively as follows:
LowerCentralSeries(G) : GrpPC -> [GrpPC]
The lower central series for the group G. The series is returned as a sequence of subgroups.
NilpotencyClass(G) : GrpPC -> RngIntElt
The nilpotency class of the group G. If G is not nilpotent, then -1 is returned.
Omega(G, i) : GrpPC, RngIntElt -> GrpPC
Given a p-group G, return the characteristic subgroup of G generated by the elements of order dividing p^i, where i is a positive integer.
pCentralSeries(G, p) : GrpPC, RngIntElt -> [GrpPC]
The p-central series for G, where p is a prime dividing |G|. The series is returned as a sequence of subgroups. The p-central series P_1 triangleright P_2 triangleright ... triangleright P_i of a soluble group G is defined inductively as follows:
SubnormalSeries(G, H) : GrpPC, GrpPC -> [GrpPC]
Given a group G and a subgroup H of G, return a sequence of subgroups commencing with G and terminating with H, such that each subgroup is normal in the previous one. If H is not subnormal in G, the empty sequence is returned.
UpperCentralSeries(G) : GrpPC -> [GrpPC]
The upper central series of G. The series is returned as a sequence of subgroups.

Example GrpPC_EAS (H19E5)

The elementary abelian series of the group D_3 wreath D_5 defined above has terms of the following sizes:

> H := DihedralGroup(GrpPerm, 5);
> G := WreathProduct(DihedralGroup(GrpPC, 3), DihedralGroup(GrpPC, 5),
>       [H.2, H.1]);
> EAS := ElementaryAbelianSeries(G);
> for i := 1 to #EAS do
>    print FactoredOrder(EAS[i]);
> end for;
	[ <2, 6>, <3, 5>, <5, 1> ]
	[ <2, 4>, <3, 5>, <5, 1> ]
	[ <2, 4>, <3, 5> ]
	[ <3, 5> ]
	[]
Hence the elementary abelian factors can be seen to have sizes 2^2, 5, 2^4, and 3^5, from top to bottom.

Subgroup Structure

MinimalNormalSubgroup(G) : GrpPC -> GrpPC
An elementary abelian minimal normal subgroup of the soluble group G.
MaximalSubgroups(G) : GrpPC -> [GrpPC]
The maximal subgroups of G returned as a sequence.
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