An equivalence relation iff G≈H, where G and H are groups
42355
Double check $G\sim H$ iff $G≈H$
98739
If $H$ is a subgroup of $G$ and $K$ is a subgroup of $H$, then $$|G:K|=|G:H||H:K|$$
89167
Cardinality of equivalence relations in $\mathbb{N}$
85507
Equivalence Relation problem
136883
The class of equivalence.
65744
How can I Prove that H=G or K=G
99538
Non-trivial groups pairwise non-isomorphic with isomorphic direct products
106927
How do I prove $[G:H\cap K]\leq [G:H][G:K]$?
114221
A Group $G$ is soluble $\iff G^{(k)}=\{e\}$ for some $k$
33294
The correspondence theorem for groups
130455
If $H,K⊲G$ and $H∩K = \{1_G\}$, then all elements in $H$ commute with all elements in $K$
150854
Identifying a quotient group (NBHM-$2014$)
24181
Showing that $G$ is a group under an alternative operation.
129452
Groups $G,H$ with surjective homomorphisms that are quotient of each other
85713
Showing Parallelism is an equivalence relation in $\Bbb R ^2$
33868
A transformation between two free group actions.
14379
Let $H \leq G$. If $G = H H^x$ then $G=H$.