Normal subgroup in S4
11731
Normal subgroups of $S_4$
116786
normal subgroups of Alternating group
137691
What are the self-normalizing subgroups of $S_n$?
75590
How many normal subgroups does a non-abelian group $G$ of order $ 21$
63780
to show characteristic subgroup is normal in G
106779
How to show if $H,K$ are normal subgroups in a group $G$ then $[H,K] \leq H \cap K$
81068
Finding the left and right cosets of H = {(1), (12), (34), (12) ○ (34)} in S4
109236
Subgroups containing kernel of group morphism to an abelian group are normal.
22444
Normal subgroups of dihedral groups
115204
Show that SO(n) is a normal subgroup of O(n)
2254
Finite group with isomorphic normal subgroups and non-isomorphic quotients?
99114
Subgroups of index 3 are normal
103423
Normal subgroup where G has order prime
88262
How to enumerate subgroups of each order of $S_4$ by hand
23941
Normal Subgroups that Intersect Trivially
15630
Normal subgroup of prime order is characteristic
151727
If $|G/H|=4$ then $G$ is union of three proper subgroups