Функторные морфизмы. Ершов А.В. - 22 стр.

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G G/H G/K.
O(G).
S(G)
x, x
X
O(G).
Aut(G/H), G/H
Aut(G/H) N
G
H/H N
G
H
H G
H G G
G H
ϕ: G/H G/H
ϕ(gH) = gϕ(eH) g G, ϕ
eH ϕ(eH) = γH γ G
γH = ϕ(eH) = ϕ(hH) = (eH) = H h H,
γ
1
Hγ H ψ := ϕ
1
. γψ(eH) = ψ(γH) = eH,
ψ(eH) = γ
1
H γHγ
1
H. H = γ
1
Hγ
γ N
G
H. γ γ
G/H γ
= γh
h H.
G
H H
H
H
G = a, b | bab
1
= a
2
H = a
2
, H
= a. γ = b
1
γ
1
H
γ H
G/H G/K.
G α: G/H G/K
α(gH) = gγK, γ G γ
1
Hγ K.
γ γ
γ
=
k h H, k K.
α(eH) = γK,
γK = α(eH) = α(hH) = (eH) = K