Proving center of group is the identity subgroup
11627
Find the center of the symmetry group $S_n$.
58707
Prove Quotient Group Isomorphism
90511
Commutator subgroup of a dihedral group.
77221
Prove that $G$ has a subgroup isomorphic to $G/H$.
129753
Prove that a subgroup which contains half of all elements is a normal subgroup.
17510
Proving a set is an abelian group.
24181
Showing that $G$ is a group under an alternative operation.
12502
The center of a non-Abelian group of order 8
80273
Prove the centralizer of an element in group $G$ is a subgroup of $G$
88221
Find the center of the group $\operatorname{GL}(n,\mathbb R)$ of invertible $n \times n$ matrices.
84198
Step in Proof of Cardinality of Product of two Groups
69820
A nontrivial p-group has nontrivial center
89234
Any Set with Associativity, Left Identity, Left Inverse is a Group
98739
If $H$ is a subgroup of $G$ and $K$ is a subgroup of $H$, then $$|G:K|=|G:H||H:K|$$
129485
A subgroup of a cyclic group is cyclic - Understanding Proof
105139
Verification of Proof that a nonabelian group G of order pq where p and q are primes has a trivial center
98542
Prove that $H$ is a subgroup of an abelian group $G$