SD₁₆ #36

order	16
nilpotency class	3
isoclinism	isoclinic class of D₈
automorphism	Aut(G) = C₂×D₄ (order 16) · Inn(G) = D₄ · Out(G) = C₂
holomorph	G ⋊ Aut(G) = #61110
homology	Abelianization (H₁) = C₂² · Schur multiplier (H₂) = C₁

Aliases

semi dihedral	SD₁₆
general semilinear	ΓL(1,𝔽₉)

	subgroup	G/H
center, socle	C₂	D₄
commutator, Frattini, cosocle	C₄	C₂²
prime radical	D₄	C₂
LCS	G ▷ C₄ ▷ C₂ ▷ C₁
UCS	C₁ ◁ C₂ ◁ C₄ ◁ G
LECS	G ▷ C₄ ▷ C₂ ▷ C₁

10 conjugacy classes of subgroups.

minimal degree	μ(G) = 8
transitive degree	μ_t(G) = 8

A minimal faithful permutation representation — 2 generators on 8 points:

(1,2,3,4,5,6,7,8);(2,4)(3,7)(6,8)

Polycyclic presentation:

2^4|a^2=d,c^2=d,b^a=bc,c^a=cd,c^b=cd

Here i is the imaginary unit (i² = −1).

Construct this group in GAP via the SmallGroups library:

gap> SmallGroup(16, 8);