Properties

Label 16.5.4.a1.a1
Order $ 2^{2} $
Index $ 2^{2} $
Normal Yes

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Subgroup ($H$) information

Description:$C_2^2$
Order: \(4\)\(\medspace = 2^{2} \)
Index: \(4\)\(\medspace = 2^{2} \)
Exponent: \(2\)
Generators: $a, b^{4}$ Copy content Toggle raw display
Nilpotency class: $1$
Derived length: $1$

The subgroup is the socle (hence characteristic and normal), central (hence abelian, nilpotent, solvable, supersolvable, monomial, metabelian, and an A-group), a $p$-group (hence elementary and hyperelementary), metacyclic, and rational.

Ambient group ($G$) information

Description: $C_2\times C_8$
Order: \(16\)\(\medspace = 2^{4} \)
Exponent: \(8\)\(\medspace = 2^{3} \)
Nilpotency class:$1$
Derived length:$1$

The ambient group is abelian (hence nilpotent, solvable, supersolvable, monomial, metabelian, and an A-group), a $p$-group (hence elementary and hyperelementary), and metacyclic.

Quotient group ($Q$) structure

Description: $C_4$
Order: \(4\)\(\medspace = 2^{2} \)
Exponent: \(4\)\(\medspace = 2^{2} \)
Automorphism Group: $C_2$, of order \(2\)
Outer Automorphisms: $C_2$, of order \(2\)
Nilpotency class: $1$
Derived length: $1$

The quotient is cyclic (hence abelian, nilpotent, solvable, supersolvable, monomial, elementary, hyperelementary, metacyclic, metabelian, a Z-group, and an A-group) and a $p$-group.

Automorphism information

Since the subgroup $H$ is characteristic, the automorphism group $\operatorname{Aut}(G)$ of the ambient group acts on $H$, yielding a homomorphism $\operatorname{res} : \operatorname{Aut}(G) \to \operatorname{Aut}(H)$. The image of $\operatorname{res}$ on the inner automorphism group $\operatorname{Inn}(G)$ is the Weyl group $W = G / Z_G(H)$.

$\operatorname{Aut}(G)$$C_2\times D_4$, of order \(16\)\(\medspace = 2^{4} \)
$\operatorname{Aut}(H)$ $S_3$, of order \(6\)\(\medspace = 2 \cdot 3 \)
$\operatorname{res}(\operatorname{Aut}(G))$$C_2$, of order \(2\)
$\card{\operatorname{ker}(\operatorname{res})}$\(8\)\(\medspace = 2^{3} \)
$W$$C_1$, of order $1$

Related subgroups

Centralizer:$C_2\times C_8$
Normalizer:$C_2\times C_8$
Minimal over-subgroups:$C_2\times C_4$
Maximal under-subgroups:$C_2$$C_2$$C_2$

Other information

Möbius function$0$
Projective image$C_4$